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/**
* Copyright (C) 2011 Ovea
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.ovea.tadjin.util.crypto;
/**
* A {@code CipherPaddingScheme} represents well-known
* padding schemes supported by JPA providers in a
* type-safe manner.
*
* 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.
*
* 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 Wikipedia: Cryptographic Padding
* @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,
* Section 5.2 - Block Encryption Algorithms.
*/
ISO10126("ISO10126Padding"),
/**
* Optimal Asymmetric Encryption Padding defined in RSA's PKSC#1
* standard (aka RFC 3447).
*
* NOTE: 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.
* Convenient Alternatives
* 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.
*
* 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
* Standard Names
* document in the Cipher Algorithm Padding 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.
*
* 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.
*
* 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.
*
* 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.
*
* 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.
*
* 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
* PKSC#1 standard (aka
* RFC 3447).
*/
PKCS1("PKCS1Padding"),
/**
* Padding scheme defined in RSA's Password-Based
* Cryptography Standard.
*/
PKCS5("PKCS5Padding"),
/**
* Padding scheme defined in the SSL
* 3.0 specification, section 5.2.3.2 (CBC block cipher).
*/
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;
}
}