diff options
Diffstat (limited to 'bcprov/src/main/java/org/bouncycastle/crypto/modes/SICBlockCipher.java')
| -rw-r--r-- | bcprov/src/main/java/org/bouncycastle/crypto/modes/SICBlockCipher.java | 177 |
1 files changed, 76 insertions, 101 deletions
diff --git a/bcprov/src/main/java/org/bouncycastle/crypto/modes/SICBlockCipher.java b/bcprov/src/main/java/org/bouncycastle/crypto/modes/SICBlockCipher.java index fbc8bf45..ae4256f6 100644 --- a/bcprov/src/main/java/org/bouncycastle/crypto/modes/SICBlockCipher.java +++ b/bcprov/src/main/java/org/bouncycastle/crypto/modes/SICBlockCipher.java @@ -6,6 +6,7 @@ import org.bouncycastle.crypto.DataLengthException; import org.bouncycastle.crypto.SkippingStreamCipher; import org.bouncycastle.crypto.StreamBlockCipher; import org.bouncycastle.crypto.params.ParametersWithIV; +import org.bouncycastle.util.Arrays; import org.bouncycastle.util.Pack; /** @@ -18,7 +19,7 @@ public class SICBlockCipher { private final BlockCipher cipher; private final int blockSize; - + private byte[] IV; private byte[] counter; private byte[] counterOut; @@ -49,8 +50,19 @@ public class SICBlockCipher if (params instanceof ParametersWithIV) { ParametersWithIV ivParam = (ParametersWithIV)params; - byte[] iv = ivParam.getIV(); - System.arraycopy(iv, 0, IV, 0, IV.length); + this.IV = Arrays.clone(ivParam.getIV()); + + if (blockSize < IV.length) + { + throw new IllegalArgumentException("CTR/SIC mode requires IV no greater than: " + blockSize + " bytes."); + } + + int maxCounterSize = (8 > blockSize / 2) ? blockSize / 2 : 8; + + if (blockSize - IV.length > maxCounterSize) + { + throw new IllegalArgumentException("CTR/SIC mode requires IV of at least: " + (blockSize - maxCounterSize) + " bytes."); + } // if null it's an IV changed only. if (ivParam.getParameters() != null) @@ -62,7 +74,7 @@ public class SICBlockCipher } else { - throw new IllegalArgumentException("SIC mode requires ParametersWithIV"); + throw new IllegalArgumentException("CTR/SIC mode requires ParametersWithIV"); } } @@ -100,94 +112,63 @@ public class SICBlockCipher { byteCount = 0; - incrementCounter(); + incrementCounterAt(0); + + checkCounter(); } return rv; } - private void incrementCounterPow2(int pow2Div8) + private void checkCounter() { - // increment counter by 1 << 8 * pow2Div8 - for (int i = counter.length - (1 + pow2Div8); i >= 0 && ++counter[i] == 0; i--) - { - ; // do nothing - pre-increment and test for 0 in counter does the job. - } - } - - private void incrementCounter(int offSet) - { - byte old = counter[counter.length - 1]; - - counter[counter.length - 1] += offSet; - - if (old != 0 && counter[counter.length - 1] < old) + // if the IV is the same as the blocksize we assume the user knows what they are doing + if (IV.length < blockSize) { - incrementCounterPow2(1); + for (int i = 0; i != IV.length; i++) + { + if (counter[i] != IV[i]) + { + throw new IllegalStateException("Counter in CTR/SIC mode out of range."); + } + } } } - private void incrementCounter() + private void incrementCounterAt(int pos) { - // increment counter by 1. - for (int i = counter.length - 1; i >= 0 && ++counter[i] == 0; i--) + int i = counter.length - pos; + while (--i >= 0) { - ; // do nothing - pre-increment and test for 0 in counter does the job. + if (++counter[i] != 0) + { + break; + } } } - private void decrementCounterPow2(int pow2Div8) + private void incrementCounter(int offSet) { - if (counter[pow2Div8] == 0) - { - boolean nonZero = false; - - for (int i = counter.length - (1 + pow2Div8); i > 0; i--) - { - if (counter[i] != 0) - { - nonZero = true; - } - } + byte old = counter[counter.length - 1]; - if (!nonZero) - { - throw new IllegalStateException("attempt to reduce counter past zero."); - } - } + counter[counter.length - 1] += offSet; - // decrement counter by 1. - for (int i = counter.length - (1 + pow2Div8); i >= 0 && --counter[i] == -1; i--) + if (old != 0 && counter[counter.length - 1] < old) { - ; + incrementCounterAt(1); } } - private void decrementCounter() + private void decrementCounterAt(int pos) { - if (counter[0] == 0) + int i = counter.length - pos; + while (--i >= 0) { - boolean nonZero = false; - - for (int i = counter.length - 1; i > 0; i--) - { - if (counter[i] != 0) - { - nonZero = true; - } - } - - if (!nonZero) + if (--counter[i] != -1) { - throw new IllegalStateException("attempt to reduce counter past zero."); + return; } } - - // decrement counter by 1. - for (int i = counter.length - 1; i >= 0 && --counter[i] == -1; i--) - { - ; - } } private void adjustCounter(long n) @@ -196,62 +177,45 @@ public class SICBlockCipher { long numBlocks = (n + byteCount) / blockSize; - if (numBlocks > 255) + long rem = numBlocks; + if (rem > 255) { - long gap = numBlocks; - for (int i = 5; i >= 1; i--) { long diff = 1L << (8 * i); - - while (gap >= diff) + while (rem >= diff) { - incrementCounterPow2(i); - - gap -= diff; + incrementCounterAt(i); + rem -= diff; } } - - incrementCounter((int)gap); - } - else - { - incrementCounter((int)numBlocks); } + incrementCounter((int)rem); + byteCount = (int)((n + byteCount) - (blockSize * numBlocks)); } else { long numBlocks = (-n - byteCount) / blockSize; - if (numBlocks > 255) + long rem = numBlocks; + if (rem > 255) { - long gap = numBlocks; - for (int i = 5; i >= 1; i--) { long diff = 1L << (8 * i); - - while (gap > diff) + while (rem > diff) { - decrementCounterPow2(i); - - gap -= diff; + decrementCounterAt(i); + rem -= diff; } } - - for (long i = 0; i != gap; i++) - { - decrementCounter(); - } } - else + + for (long i = 0; i != rem; i++) { - for (long i = 0; i != numBlocks; i++) - { - decrementCounter(); - } + decrementCounterAt(0); } int gap = (int)(byteCount + n + (blockSize * numBlocks)); @@ -262,7 +226,7 @@ public class SICBlockCipher } else { - decrementCounter(); + decrementCounterAt(0); byteCount = blockSize + gap; } } @@ -270,7 +234,8 @@ public class SICBlockCipher public void reset() { - System.arraycopy(IV, 0, counter, 0, counter.length); + Arrays.fill(counter, (byte)0); + System.arraycopy(IV, 0, counter, 0, IV.length); cipher.reset(); this.byteCount = 0; } @@ -279,6 +244,8 @@ public class SICBlockCipher { adjustCounter(numberOfBytes); + checkCounter(); + cipher.processBlock(counter, 0, counterOut, 0); return numberOfBytes; @@ -293,13 +260,21 @@ public class SICBlockCipher public long getPosition() { - byte[] res = new byte[IV.length]; + byte[] res = new byte[counter.length]; System.arraycopy(counter, 0, res, 0, res.length); for (int i = res.length - 1; i >= 1; i--) { - int v = (res[i] & 0xff) - (IV[i] & 0xff); + int v; + if (i < IV.length) + { + v = (res[i] & 0xff) - (IV[i] & 0xff); + } + else + { + v = (res[i] & 0xff); + } if (v < 0) { |