PaddingScheme.java
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package org.apache.shiro.crypto;
/**
* A {@code CipherPaddingScheme} represents well-known
* <a href="http://en.wikipedia.org/wiki/Padding_(cryptography)">padding schemes</a> supported by JPA providers in a
* type-safe manner.
* <p/>
* When encrypted data is transferred, it is usually desirable to ensure that all 'chunks' transferred are a fixed-length:
* different length blocks might give cryptanalysts clues about what the data might be, among other reasons. Of course
* not all data will convert to neat fixed-length blocks, so padding schemes are used to 'fill in' (pad) any remaining
* space with unintelligible data.
* <p/>
* Padding schemes can be used in both asymmetric key ciphers as well as symmetric key ciphers (e.g. block ciphers).
* Block-ciphers especially regularly use padding schemes as they are based on the notion of fixed-length block sizes.
*
* @see <a href="http://en.wikipedia.org/wiki/Padding_(cryptography)">Wikipedia: Cryptographic Padding</a>
* @since 1.0
*/
public enum PaddingScheme {
/**
* No padding. Useful when the block size is 8 bits for block cipher streaming operations. (Because
* a byte is the most primitive block size, there is nothing to pad).
*/
NONE("NoPadding"),
/**
* Padding scheme as defined in the W3C's "XML Encryption Syntax and Processing" document,
* <a href="http://www.w3.org/TR/xmlenc-core/#sec-Alg-Block">Section 5.2 - Block Encryption Algorithms</a>.
*/
ISO10126("ISO10126Padding"),
/**
* Optimal Asymmetric Encryption Padding defined in RSA's <a href="http://en.wikipedia.org/wiki/PKCS1">PKSC#1
* standard</a> (aka <a href="http://tools.ietf.org/html/rfc3447">RFC 3447</a>).
* <p/>
* <b>NOTE:</b> using this padding requires initializing {@link javax.crypto.Cipher Cipher} instances with a
* {@link javax.crypto.spec.OAEPParameterSpec OAEPParameterSpec} object which provides the 1) message digest and
* 2) mask generation function to use for the scheme.
* <h3>Convenient Alternatives</h3>
* While using this scheme enables you full customization of the message digest + mask generation function
* combination, it does require the extra burden of providing your own {@code OAEPParameterSpec} object. This is
* often unnecessary, because most combinations are fairly standard. These common combinations are pre-defined
* in this enum in the {@code OAEP}* variants.
* <p/>
* If you find that these common combinations still do not meet your needs, then you will need to
* specify your own message digest and mask generation function, either as an {@code OAEPParameterSpec} object
* during Cipher initialization or, maybe more easily, in the scheme name directly. If you want to use scheme name
* approach, the name format is specified in the
* <a href="http://java.sun.com/javase/6/docs/technotes/guides/security/StandardNames.html">Standard Names</a>
* document in the <code>Cipher Algorithm Padding</code> section.
*
* @see #OAEPWithMd5AndMgf1
* @see #OAEPWithSha1AndMgf1
* @see #OAEPWithSha256AndMgf1
* @see #OAEPWithSha384AndMgf1
* @see #OAEPWithSha512AndMgf1
*/
OAEP("OAEPPadding"),
/**
* Optimal Asymmetric Encryption Padding with {@code MD5} message digest and {@code MGF1} mask generation function.
* <p/>
* This is a convenient pre-defined OAEP padding scheme that embeds the message digest and mask generation function.
* When using this padding scheme, there is no need to init the {@code Cipher} instance with an
* {@link javax.crypto.spec.OAEPParameterSpec OAEPParameterSpec} object, as it is already 'built in' to the scheme
* name (unlike the {@link #OAEP OAEP} scheme, which requires a bit more work).
*/
OAEPWithMd5AndMgf1("OAEPWithMD5AndMGF1Padding"),
/**
* Optimal Asymmetric Encryption Padding with {@code SHA-1} message digest and {@code MGF1} mask generation function.
* <p/>
* This is a convenient pre-defined OAEP padding scheme that embeds the message digest and mask generation function.
* When using this padding scheme, there is no need to init the {@code Cipher} instance with an
* {@link javax.crypto.spec.OAEPParameterSpec OAEPParameterSpec} object, as it is already 'built in' to the scheme
* name (unlike the {@link #OAEP OAEP} scheme, which requires a bit more work).
*/
OAEPWithSha1AndMgf1("OAEPWithSHA-1AndMGF1Padding"),
/**
* Optimal Asymmetric Encryption Padding with {@code SHA-256} message digest and {@code MGF1} mask generation function.
* <p/>
* This is a convenient pre-defined OAEP padding scheme that embeds the message digest and mask generation function.
* When using this padding scheme, there is no need to init the {@code Cipher} instance with an
* {@link javax.crypto.spec.OAEPParameterSpec OAEPParameterSpec} object, as it is already 'built in' to the scheme
* name (unlike the {@link #OAEP OAEP} scheme, which requires a bit more work).
*/
OAEPWithSha256AndMgf1("OAEPWithSHA-256AndMGF1Padding"),
/**
* Optimal Asymmetric Encryption Padding with {@code SHA-384} message digest and {@code MGF1} mask generation function.
* <p/>
* This is a convenient pre-defined OAEP padding scheme that embeds the message digest and mask generation function.
* When using this padding scheme, there is no need to init the {@code Cipher} instance with an
* {@link javax.crypto.spec.OAEPParameterSpec OAEPParameterSpec} object, as it is already 'built in' to the scheme
* name (unlike the {@link #OAEP OAEP} scheme, which requires a bit more work).
*/
OAEPWithSha384AndMgf1("OAEPWithSHA-384AndMGF1Padding"),
/**
* Optimal Asymmetric Encryption Padding with {@code SHA-512} message digest and {@code MGF1} mask generation function.
* <p/>
* This is a convenient pre-defined OAEP padding scheme that embeds the message digest and mask generation function.
* When using this padding scheme, there is no need to init the {@code Cipher} instance with an
* {@link javax.crypto.spec.OAEPParameterSpec OAEPParameterSpec} object, as it is already 'built in' to the scheme
* name (unlike the {@link #OAEP OAEP} scheme, which requires a bit more work).
*/
OAEPWithSha512AndMgf1("OAEPWithSHA-512AndMGF1Padding"),
/**
* Padding scheme used with the {@code RSA} algorithm defined in RSA's
* <a href="http://en.wikipedia.org/wiki/PKCS1">PKSC#1 standard</a> (aka
* <a href="http://tools.ietf.org/html/rfc3447">RFC 3447</a>).
*/
PKCS1("PKCS1Padding"),
/**
* Padding scheme defined in RSA's <a href="http://www.rsa.com/rsalabs/node.asp?id=2127">Password-Based
* Cryptography Standard</a>.
*/
PKCS5("PKCS5Padding"),
/**
* Padding scheme defined in the <a href="http://www.mozilla.org/projects/security/pki/nss/ssl/draft302.txt">SSL
* 3.0 specification</a>, section <code>5.2.3.2 (CBC block cipher)</code>.
*/
SSL3("SSL3Padding");
private final String transformationName;
private PaddingScheme(String transformationName) {
this.transformationName = transformationName;
}
/**
* Returns the actual string name to use when building the {@link javax.crypto.Cipher Cipher}
* {@code transformation string}.
*
* @return the actual string name to use when building the {@link javax.crypto.Cipher Cipher}
* {@code transformation string}.
* @see javax.crypto.Cipher#getInstance(String)
*/
public String getTransformationName() {
return this.transformationName;
}
}