RSA Class

Properties   Methods   Events   Config Settings   Errors  

Implements RSA public-key cryptography to encrypt/decrypt and sign/verify messages.

Syntax

ipworksencrypt.RSA

Remarks

The RSA class implements RSA public-key cryptography to encrypt/decrypt messages and sign/verify hash signatures.

To begin you must either specify an existing key or create a new key. Existing private keys may be specified by setting Key. To create a new key call CreateKey. Alternatively an existing certificate may be specified by setting Certificate

Signing

To sign data first set Key or Certificate. Specify the input data using InputFile or InputMessage. Next call Sign. The class will populate HashValue and HashSignature. After calling Sign the public key must be sent to the recipient along with HashSignature.

Encrypting

To encrypt data set RecipientKey or RecipientCert. Specify the input data using InputFile or InputMessage. Next call Encrypt. The class will populate OutputMessage, or write to the file specified by OutputFile.

Signature Verification

To verify a signature specify the input data using InputFile or InputMessage. Set SignerKey or SignerCert. Next set HashSignature and call VerifySignature. The VerifySignature method will return True if the signature was successfully verified.

Decrypting

To decrypt data first set Key or Certificate. Specify the input data using InputFile or InputMessage. Next call Decrypt. The class will populate OutputMessage, or write to the file specified by OutputFile.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

RSA Keys

A RSA key is made up of a number of individual parameters.

The public key consists of the following parameters:

• Modulus
• Exponent

The class also includes the PublicKey field which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both sides of the encryption/signing and decryption/signature verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key may be represented in one of two ways. Both are mathematically equivalent. Private key format 1:

• Modulus
• P
• Q
• DP
• DQ

Private key format 2 is simpler but has decreased performance when decrypting and signing. This format is:

• Modulus
• D

The class also include the PrivateKey field which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Property List

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The following is the full list of the properties of the class with short descriptions. Click on the links for further details.

Method List

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The following is the full list of the methods of the class with short descriptions. Click on the links for further details.

Event List

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The following is the full list of the events fired by the class with short descriptions. Click on the links for further details.

Config Settings

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The following is a list of config settings for the class with short descriptions. Click on the links for further details.

Certificate Property (RSA Class)

The certificate used for signing and decryption.

Syntax

public Certificate getCertificate();
public void setCertificate(Certificate certificate);

Remarks

This property specifies a certificate with private key.

This may be set instead of Key. This allows a Certificate object to be used instead of a RSAKey object. This certificate is used when calling Sign and Decrypt. The specified certificate must have a private key.

If both this property and Key are specified, Key will be used and this property will be ignored.

Please refer to the Certificate type for a complete list of fields.

HashAlgorithm Property (RSA Class)

The hash algorithm used for signing and signature verification.

Syntax

public int getHashAlgorithm();
public void setHashAlgorithm(int hashAlgorithm);

Enumerated values:
  public final static int rhaSHA1 = 0;
  public final static int rhaSHA224 = 1;
  public final static int rhaSHA256 = 2;
  public final static int rhaSHA384 = 3;
  public final static int rhaSHA512 = 4;
  public final static int rhaRIPEMD160 = 5;
  public final static int rhaMD2 = 6;
  public final static int rhaMD5 = 7;
  public final static int rhaMD5SHA1 = 8;

Default Value

2

Remarks

This property specifies the hash algorithm used for signing and signature verification. Possible values are:

HashSignature Property (RSA Class)

The hash signature.

Syntax

public byte[] getHashSignature();
public void setHashSignature(byte[] hashSignature);

Default Value

""

Remarks

This property holds the computed hash signature. This is populated after calling Sign. This must be set before calling VerifySignature.

HashValue Property (RSA Class)

The hash value of the data.

Syntax

public byte[] getHashValue();
public void setHashValue(byte[] hashValue);

Default Value

""

Remarks

This property holds the computed hash value for the specified data. This is populated when calling Sign or VerifySignature when an input file is specified by setting SetInputStream, InputFile, or InputMessage.

If you know the hash value prior to using the class you may specify the pre-computed hash value here.

Hash Notes

The class will determine whether or not to recompute the hash based on the properties that are set. If a file is specified by SetInputStream, InputFile, or InputMessage, the hash will be recomputed when calling Sign or VerifySignature. If the HashValue property is set, the class will only sign the hash or verify the hash signature. Setting SetInputStream, InputFile, or InputMessage clears the HashValue property. Setting the HashValue property clears the input file selection.

InputFile Property (RSA Class)

The file to process.

Syntax

public String getInputFile();
public void setInputFile(String inputFile);

Default Value

""

Remarks

This property specifies the file to be processed. Set this property to the full or relative path to the file which will be processed.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

InputMessage Property (RSA Class)

The message to process.

Syntax

public byte[] getInputMessage();
public void setInputMessage(byte[] inputMessage);

Default Value

""

Remarks

This property specifies the message to be processed.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

Key Property (RSA Class)

The RSA key.

Syntax

public RSAKey getKey();
public void setKey(RSAKey key);

Remarks

This property specifies the RSA key used to sign or decrypt data. This property must be set before calling Sign or Decrypt. Alternatively, a certificate may be specified by setting Certificate

RSA Keys

A RSA key is made up of a number of individual parameters.

The public key consists of the following parameters:

• Modulus
• Exponent

The class also includes the PublicKey field which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both sides of the encryption/signing and decryption/signature verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key may be represented in one of two ways. Both are mathematically equivalent. Private key format 1:

• Modulus
• P
• Q
• DP
• DQ

Private key format 2 is simpler but has decreased performance when decrypting and signing. This format is:

• Modulus
• D

The class also include the PrivateKey field which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Please refer to the RSAKey type for a complete list of fields.

OutputFile Property (RSA Class)

The output file when encrypting or decrypting.

Syntax

public String getOutputFile();
public void setOutputFile(String outputFile);

Default Value

""

Remarks

This property specifies the file to which the output will be written when Encrypt or Decrypt is called. This may be set to an absolute or relative path.

This property is only applicable to Encrypt and Decrypt.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

OutputMessage Property (RSA Class)

The output message after processing.

Syntax

public byte[] getOutputMessage();

Default Value

""

Remarks

This property will be populated with the output from the operation if OutputFile and SetOutputStream are not set.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

This property is read-only and not available at design time.

Overwrite Property (RSA Class)

Indicates whether or not the class should overwrite files.

Syntax

public boolean isOverwrite();
public void setOverwrite(boolean overwrite);

Default Value

False

Remarks

This property indicates whether or not the class will overwrite OutputFile. If Overwrite is False, an error will be thrown whenever OutputFile exists before an operation. The default value is False.

RecipientCert Property (RSA Class)

The certificate used for encryption.

Syntax

public Certificate getRecipientCert();
public void setRecipientCert(Certificate recipientCert);

Remarks

This property specifies a certificate for encryption.

This may be set instead of RecipientKey. This allows a Certificate object to be used instead of a RSAKey object. This certificate is used when calling Encrypt.

If both this property and RecipientKey are specified, RecipientKey will be used and this property will be ignored.

Please refer to the Certificate type for a complete list of fields.

RecipientKey Property (RSA Class)

The recipient's public key used when encrypting.

Syntax

public RSAKey getRecipientKey();
public void setRecipientKey(RSAKey recipientKey);

Remarks

This property specifies the recipient's public key. This property must be set before calling Encrypt. Alternatively, a certificate may be specified by setting RecipientCert

RSA Keys

A RSA key is made up of a number of individual parameters.

The public key consists of the following parameters:

• Modulus
• Exponent

The class also includes the PublicKey field which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both sides of the encryption/signing and decryption/signature verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key may be represented in one of two ways. Both are mathematically equivalent. Private key format 1:

• Modulus
• P
• Q
• DP
• DQ

Private key format 2 is simpler but has decreased performance when decrypting and signing. This format is:

• Modulus
• D

The class also include the PrivateKey field which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Please refer to the RSAKey type for a complete list of fields.

SignerCert Property (RSA Class)

The certificate used for signature verification.

Syntax

public Certificate getSignerCert();
public void setSignerCert(Certificate signerCert);

Remarks

This property specifies a certificate for signature verification.

This may be set instead of SignerKey. This allows a Certificate object to be used instead of a RSAKey object. This certificate is used when calling VerifySignature.

If both this property and SignerKey are specified, SignerKey will be used and this property will be ignored.

Please refer to the Certificate type for a complete list of fields.

SignerKey Property (RSA Class)

The public key used to verify the signature.

Syntax

public RSAKey getSignerKey();
public void setSignerKey(RSAKey signerKey);

Remarks

This property specifies the public key used to verify the signature. This public key corresponds to the private key used when creating the signature. This must be set before calling VerifySignature. Alternatively, a certificate may be specified by setting SignerCert

RSA Keys

A RSA key is made up of a number of individual parameters.

The public key consists of the following parameters:

• Modulus
• Exponent

The class also includes the PublicKey field which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both sides of the encryption/signing and decryption/signature verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key may be represented in one of two ways. Both are mathematically equivalent. Private key format 1:

• Modulus
• P
• Q
• DP
• DQ

Private key format 2 is simpler but has decreased performance when decrypting and signing. This format is:

• Modulus
• D

The class also include the PrivateKey field which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Please refer to the RSAKey type for a complete list of fields.

UseHex Property (RSA Class)

Whether input or output is hex encoded.

Syntax

public boolean isUseHex();
public void setUseHex(boolean useHex);

Default Value

False

Remarks

This property specifies whether the encrypted data, HashValue, and HashSignature are hex encoded.

If set to True, when Encrypt is called the class will perform the encryption as normal and then hex encode the output. OutputMessage or OutputFile will hold hex encoded data.

If set to True, when Decrypt is called the class will expect InputMessage or InputFile to hold hex encoded data. The class will then hex decode the data and perform decryption as normal.

If set to True, when Sign is called the class will compute the hash for the specified file and populate HashValue with the hex encoded hash value. It will then create the hash signature and populate HashSignature with the hex encoded hash signature value. If HashValue is specified directly, it must be a hex encoded value.

If set to True, when VerifySignature is called the class will compute the hash value for the specified file and populate HashValue with the hex encoded hash value. It will then hex decode HashSignature and verify the signature. HashSignature must hold a hex encoded value. If HashValue is specified directly, it must be a hex encoded value.

UseOAEP Property (RSA Class)

Whether to use Optimal Asymmetric Encryption Padding (OAEP).

Syntax

public boolean isUseOAEP();
public void setUseOAEP(boolean useOAEP);

Default Value

False

Remarks

Whether to use Optimal Asymmetric Encryption Padding (OAEP). By default this value is False and the class will use PKCS1.

Note: When set to True the HashAlgorithm is also applicable when calling Encrypt and Decrypt.

UsePSS Property (RSA Class)

Whether to use RSA-PSS during signing and verification.

Syntax

public boolean isUsePSS();
public void setUsePSS(boolean usePSS);

Default Value

False

Remarks

This property specifies whether RSA-PSS will be used when signing and verifying messages. The default value is False.

Config Method (RSA Class)

Sets or retrieves a configuration setting.

Syntax

public String config(String configurationString);

Remarks

Config is a generic method available in every class. It is used to set and retrieve configuration settings for the class.

These settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

To set a configuration setting named PROPERTY, you must call Config("PROPERTY=VALUE"), where VALUE is the value of the setting expressed as a string. For boolean values, use the strings "True", "False", "0", "1", "Yes", or "No" (case does not matter).

To read (query) the value of a configuration setting, you must call Config("PROPERTY"). The value will be returned as a string.

CreateKey Method (RSA Class)

Creates a new key.

Syntax

public void createKey();

Remarks

This method creates a new public and private key.

When calling CreateKey the Key property is populated with a new private and public key.

RSA Keys

A RSA key is made up of a number of individual parameters.

The public key consists of the following parameters:

• Modulus
• Exponent

The class also includes the PublicKey field which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both sides of the encryption/signing and decryption/signature verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key may be represented in one of two ways. Both are mathematically equivalent. Private key format 1:

• Modulus
• P
• Q
• DP
• DQ

Private key format 2 is simpler but has decreased performance when decrypting and signing. This format is:

• Modulus
• D

The class also include the PrivateKey field which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Decrypt Method (RSA Class)

Decrypts the input data using the specified private key.

Syntax

public void decrypt();

Remarks

This method decrypts the input data using the private key specified in Key. Alternatively, a certificate may be specified by setting Certificate.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

Key Size and the Maximum Length of Data

RSA has an upper limit to the amount of data that can be encrypted or decrypted, also known as message length. This can typically be calculated as the size of the key minus the size of the RSA header and padding.

When not using OAEP, the following formula and table can be referenced. (RSA Key Bytes) - (Header Bytes) = Length of data, where Header Bytes is always 11.

When using OAEP, the following formula and table can be referenced. (RSA Key Bytes) - (2 * Hash Length Bytes) - 2 = Length of data. The table below assumes SHA-256 for the hash, so Hash Length Bytes is 32.

Encrypt Method (RSA Class)

Encrypts the input data using the recipient's public key.

Syntax

public void encrypt();

Remarks

This method encrypts the input data using the public key specified in RecipientKey. Alternatively, a certificate may be specified by setting RecipientCert.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

Key Size and the Maximum Length of Data

RSA has an upper limit to the amount of data that can be encrypted or decrypted, also known as message length. This can typically be calculated as the size of the key minus the size of the RSA header and padding.

When not using OAEP, the following formula and table can be referenced. (RSA Key Bytes) - (Header Bytes) = Length of data, where Header Bytes is always 11.

When using OAEP, the following formula and table can be referenced. (RSA Key Bytes) - (2 * Hash Length Bytes) - 2 = Length of data. The table below assumes SHA-256 for the hash, so Hash Length Bytes is 32.

Reset Method (RSA Class)

Resets the class.

Syntax

public void reset();

Remarks

When called, the class will reset all of its properties to their default values.

SetInputStream Method (RSA Class)

Sets the stream from which the class will read data to encrypt or decrypt.

Syntax

public void setInputStream(java.io.InputStream inputStream);

Remarks

This method sets the stream from which the class will read data to encrypt or decrypt.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

SetOutputStream Method (RSA Class)

Sets the stream to which the class will write encrypted or decrypted data.

Syntax

public void setOutputStream(java.io.OutputStream outputStream);

Remarks

This method sets the stream to which the class will write encrypted or decrypted data.

Input and Output Properties

The class will determine the source and destination of the input and output based on which properties are set.

The order in which the input properties are checked is as follows:

• SetInputStream
• InputFile
• InputMessage

When a valid source is found, the search stops. The order in which the output properties are checked is as follows:

• SetOutputStream
• OutputFile
• OutputMessage: The output data is written to this property if no other destination is specified.

When using streams, you may need to additionally set CloseInputStreamAfterProcessing or CloseOutputStreamAfterProcessing.

Sign Method (RSA Class)

Creates a hash signature.

Syntax

public void sign();

Remarks

This method will create a hash signature.

Before calling this method specify the input file by setting SetInputStream, InputFile, or InputMessage.

A key is required to create the hash signature. You may create a new key by calling CreateKey, or specify an existing key pair in Key. Alternatively, a certificate may be specified by setting Certificate. When this method is called the class will compute the hash for the specified file and populate HashValue. It will then create the hash signature using the specified Key and populate HashSignature.

To create the hash signature without first computing the hash simply specify HashValue before calling this method.

The Progress event will fire with updates for the hash computation progress only. The hash signature creation process is quick and does not require progress updates.

VerifySignature Method (RSA Class)

Verifies the signature for the specified data.

Syntax

public boolean verifySignature();

Remarks

This method will verify a hash signature.

Before calling this method specify the input file by setting SetInputStream, InputFile, or InputMessage.

A public key and the hash signature are required to perform the signature verification. Specify the public key in SignerKey. Alternatively, a certificate may be specified by setting SignerCert. Specify the hash signature in HashSignature.

When this method is called the class will compute the hash for the specified file and populate HashValue. It will verify the signature using the specified SignerKey and HashSignature.

To verify the hash signature without first computing the hash simply specify HashValue before calling this method.

The Progress event will fire with updates for the hash computation progress only. The hash signature verification process is quick and does not require progress updates.

Error Event (RSA Class)

Fired when information is available about errors during data delivery.

Syntax

public class DefaultRSAEventListener implements RSAEventListener {
  ...
  public void error(RSAErrorEvent e) {}
  ...
}

public class RSAErrorEvent {
  public int errorCode;
  public String description;
}

Remarks

The Error event is fired in case of exceptional conditions during message processing. Normally the class throws an exception.

The ErrorCode parameter contains an error code, and the Description parameter contains a textual description of the error. For a list of valid error codes and their descriptions, please refer to the Error Codes section.

Progress Event (RSA Class)

Fired as progress is made.

Syntax

public class DefaultRSAEventListener implements RSAEventListener {
  ...
  public void progress(RSAProgressEvent e) {}
  ...
}

public class RSAProgressEvent {
  public long bytesProcessed;
  public int percentProcessed;
}

Remarks

This event is fired automatically as data is processed by the class.

The PercentProcessed parameter indicates the current status of the operation.

The BytesProcessed parameter holds the total number of bytes processed so far.

Certificate Type

This is the digital certificate being used.

Remarks

This type describes the current digital certificate. The certificate may be a public or private key. The fields are used to identify or select certificates.

Fields

Constructors

public Certificate();

public Certificate( certificateFile);

public Certificate( encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

public Certificate( storeType,  store,  storePassword,  subject);

public Certificate( storeType,  store,  storePassword,  subject,  configurationString);

public Certificate( storeType,  store,  storePassword,  encoded);

RSAKey Type

Contains the typical parameters for the RSA algorithm.

Remarks

This type is made up of fields that represent the private and public key parameters used by the RSA algorithm.

RSA Keys

A RSA key is made up of a number of individual parameters.

The public key consists of the following parameters:

• Modulus
• Exponent

The class also includes the PublicKey field which holds the PEM formatted public key for ease of use. This is helpful if you are in control of both sides of the encryption/signing and decryption/signature verification process. When sending the public key to a recipient note that not all implementations will support using the PEM formatted value in PublicKey in which case the individual parameters must be sent.

The private key may be represented in one of two ways. Both are mathematically equivalent. Private key format 1:

• Modulus
• P
• Q
• DP
• DQ

Private key format 2 is simpler but has decreased performance when decrypting and signing. This format is:

• Modulus
• D

The class also include the PrivateKey field which holds the PEM formatted private key for ease of use. This is helpful for storing the private key more easily.

Fields

Constructors

public RSAKey();

public RSAKey( modulus,  exponent);

public RSAKey( modulus,  D,  P,  Q,  DP,  DQ);

Config Settings (RSA Class)

The class accepts one or more of the following configuration settings. Configuration settings are similar in functionality to properties, but they are rarely used. In order to avoid "polluting" the property namespace of the class, access to these internal properties is provided through the Config method.

RSA Config Settings

Base Config Settings

Trappable Errors (RSA Class)

RSA Errors