Example usage for org.bouncycastle.crypto.util Pack bigEndianToInt

Introduction

In this page you can find the example usage for org.bouncycastle.crypto.util Pack bigEndianToInt.

Prototype

public static int bigEndianToInt(byte[] bs, int off) 

Source Link

Usage

From source file:com.licel.jcardsim.crypto.MessageDigestImpl.java

License:Apache License

public void setInitialDigest(byte[] initialDigestBuf, short initialDigestOffset, short initialDigestLength,
        byte[] digestedMsgLenBuf, short digestedMsgLenOffset, short digestedMsgLenLength)
        throws CryptoException {
    // initialDigestLength must be == DIGEST_SIZE
    if (engine.getDigestSize() != initialDigestLength) {
        CryptoException.throwIt(CryptoException.ILLEGAL_VALUE);
    }/*from  ww w  . ja va  2 s .c  o  m*/
    // digestedMsgLenLength must be > 0 and < long value, more formal 2^64-1 bits
    // TODO support length more 2^128-1 bits (SHA-384, SHA-512) 
    if (digestedMsgLenLength == 0 || digestedMsgLenLength > 8) {
        CryptoException.throwIt(CryptoException.ILLEGAL_VALUE);
    }
    long byteCount = 0;
    for (short i = 0; i < digestedMsgLenLength; i++) {
        byteCount = (byteCount << 8) + (digestedMsgLenBuf[digestedMsgLenOffset + i] & 0xff);
    }
    // byte count % block size must be == 0
    if (byteCount % blockSize != 0) {
        CryptoException.throwIt(CryptoException.ILLEGAL_VALUE);
    }
    // set hash state - BouncyCastle specific
    try {
        for (byte i = 0; i < componentCount; i++) {
            // some reflection work
            Field h = digestClass.getDeclaredField("H" + (i + componentStartIdx));
            h.setAccessible(true);
            if (componentSize == 4) {
                h.setInt(engine,
                        Pack.bigEndianToInt(initialDigestBuf, initialDigestOffset + i * componentSize));
            } else {
                h.setLong(engine,
                        Pack.bigEndianToLong(initialDigestBuf, initialDigestOffset + i * componentSize));
            }
        }
        // set byteCount
        Field h = digestClass.getSuperclass().getDeclaredField(byteCountFieldName);
        h.setAccessible(true);
        h.setLong(engine, byteCount);
    } catch (Exception e) {
        CryptoException.throwIt(CryptoException.ILLEGAL_USE);
    }
}

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