com.ibm.crypto.fips.provider

Class RSAPadding

java.lang.Object

com.ibm.crypto.fips.provider.RSAPadding

public final class RSAPadding
extends java.lang.Object

RSA padding and unpadding. The various PKCS#1 versions can be found in the EMC/RSA Labs web site, which is currently: http://www.emc.com/emc-plus/rsa-labs/index.htm or in the IETF RFCs derived from the above PKCS#1 standards. RFC 2313: v1.5 RFC 2437: v2.0 RFC 3447: v2.1 The format of PKCS#1 v1.5 padding is: 0x00 | BT | PS...PS | 0x00 | data...data where BT is the blocktype (1 or 2). The length of the entire string must be the same as the size of the modulus (i.e. 128 byte for a 1024 bit key). Per spec, the padding string must be at least 8 bytes long. That leaves up to (length of key in bytes) - 11 bytes for the data. OAEP padding was introduced in PKCS#1 v2.0 and is a bit more complicated and has a number of options. We support: . arbitrary hash functions ('Hash' in the specification), MessageDigest implementation must be available . MGF1 as the mask generation function . the empty string as the default value for label L and whatever specified in javax.crypto.spec.OAEPParameterSpec The algorithms (representations) are forwards-compatible: that is, the algorithm described in previous releases are in later releases. However, additional comments/checks/clarifications were added to the later versions based on real-world experience (e.g. stricter v1.5 format checking.) Note: RSA keys should be at least 512 bits long

Since:

1.5

Field Summary

Fields

Modifier and Type	Field and Description
static int	PAD_BLOCKTYPE_1
static int	PAD_BLOCKTYPE_2
static int	PAD_NONE
static int	PAD_OAEP_MGF1
static int	PAD_ZERO

Method Summary

Methods

Modifier and Type	Method and Description
static RSAPadding	getInstance(int type, int paddedSize) Get a RSAPadding instance of the specified type.
static RSAPadding	getInstance(int type, int paddedSize, java.security.SecureRandom random) Get a RSAPadding instance of the specified type.
static RSAPadding	getInstance(int type, int paddedSize, java.security.SecureRandom random, javax.crypto.spec.OAEPParameterSpec spec) Get a RSAPadding instance of the specified type, which must be OAEP.
int	getMaxDataSize() Return the maximum size of the plaintext data that can be processed using this object.
byte[]	pad(byte[] data) Pad the data and return the padded block.
byte[]	pad(byte[] data, int ofs, int len) Pad the data and return the padded block.
byte[]	unpad(byte[] padded) Unpad the padded block and return the data.
byte[]	unpad(byte[] padded, int ofs, int len) Unpad the padded block and return the data.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

PAD_BLOCKTYPE_1

public static final int PAD_BLOCKTYPE_1

See Also:

Constant Field Values

PAD_BLOCKTYPE_2

public static final int PAD_BLOCKTYPE_2

See Also:

Constant Field Values

PAD_NONE

public static final int PAD_NONE

See Also:

Constant Field Values

PAD_OAEP_MGF1

public static final int PAD_OAEP_MGF1

See Also:

Constant Field Values

PAD_ZERO

public static final int PAD_ZERO

See Also:

Constant Field Values

Method Detail

getInstance

public static RSAPadding getInstance(int type,
                     int paddedSize)
                              throws java.security.InvalidKeyException,
                                     java.security.InvalidAlgorithmParameterException

Get a RSAPadding instance of the specified type. Keys used with this padding must be paddedSize bytes long.

Throws:

java.security.InvalidKeyException

java.security.InvalidAlgorithmParameterException

getInstance

public static RSAPadding getInstance(int type,
                     int paddedSize,
                     java.security.SecureRandom random)
                              throws java.security.InvalidKeyException,
                                     java.security.InvalidAlgorithmParameterException

Get a RSAPadding instance of the specified type. Keys used with this padding must be paddedSize bytes long.

Throws:

java.security.InvalidKeyException

java.security.InvalidAlgorithmParameterException

getInstance

public static RSAPadding getInstance(int type,
                     int paddedSize,
                     java.security.SecureRandom random,
                     javax.crypto.spec.OAEPParameterSpec spec)
                              throws java.security.InvalidKeyException,
                                     java.security.InvalidAlgorithmParameterException

Get a RSAPadding instance of the specified type, which must be OAEP. Keys used with this padding must be paddedSize bytes long.

Throws:

java.security.InvalidKeyException

java.security.InvalidAlgorithmParameterException

getMaxDataSize

public int getMaxDataSize()

Return the maximum size of the plaintext data that can be processed using this object.

pad

public byte[] pad(byte[] data,
         int ofs,
         int len)
           throws javax.crypto.BadPaddingException

Pad the data and return the padded block.

Throws:

javax.crypto.BadPaddingException

pad

public byte[] pad(byte[] data)
           throws javax.crypto.BadPaddingException

Pad the data and return the padded block.

Throws:

javax.crypto.BadPaddingException

unpad

public byte[] unpad(byte[] padded,
           int ofs,
           int len)
             throws javax.crypto.BadPaddingException

Unpad the padded block and return the data.

Throws:

javax.crypto.BadPaddingException

unpad

public byte[] unpad(byte[] padded)
             throws javax.crypto.BadPaddingException

Unpad the padded block and return the data.

Throws:

javax.crypto.BadPaddingException