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| author | Peter Dettman <peter.dettman@bouncycastle.org> | 2015-11-09 19:25:07 +0700 |
|---|---|---|
| committer | Peter Dettman <peter.dettman@bouncycastle.org> | 2015-11-09 19:25:07 +0700 |
| commit | bf9600f6e8c3e8c83ba95a5e0821ec78e270cfa0 (patch) | |
| tree | 6d8db3686653c7350ac306c7a180486f666458d2 | |
| parent | Add contributor entries (diff) | |
| download | BouncyCastle.NET-ed25519-bf9600f6e8c3e8c83ba95a5e0821ec78e270cfa0.tar.xz | |
Improve random prime constructor
| -rw-r--r-- | crypto/src/math/BigInteger.cs | 18 |
1 files changed, 7 insertions, 11 deletions
diff --git a/crypto/src/math/BigInteger.cs b/crypto/src/math/BigInteger.cs index 3d0509fe0..2ca3da978 100644 --- a/crypto/src/math/BigInteger.cs +++ b/crypto/src/math/BigInteger.cs @@ -681,6 +681,7 @@ namespace Org.BouncyCastle.Math int xBits = BitsPerByte * nBytes - bitLength; byte mask = (byte)(255U >> xBits); + byte lead = (byte)(1 << (7 - xBits)); for (;;) { @@ -690,7 +691,7 @@ namespace Org.BouncyCastle.Math b[0] &= mask; // ensure the leading bit is 1 (to meet the strength requirement) - b[0] |= (byte)(1 << (7 - xBits)); + b[0] |= lead; // ensure the trailing bit is 1 (i.e. must be odd) b[nBytes - 1] |= 1; @@ -705,18 +706,13 @@ namespace Org.BouncyCastle.Math if (CheckProbablePrime(certainty, random, true)) break; - if (bitLength > 32) + for (int j = 1; j < magnitude.Length; ++j) { - for (int rep = 0; rep < 10000; ++rep) - { - int n = 33 + random.Next(bitLength - 2); - this.magnitude[this.magnitude.Length - (n >> 5)] ^= (1 << (n & 31)); - this.magnitude[this.magnitude.Length - 1] ^= ((random.Next() + 1) << 1); - this.mQuote = 0; + this.magnitude[j] ^= (random.Next() << 1); + this.mQuote = 0; - if (CheckProbablePrime(certainty, random, true)) - return; - } + if (CheckProbablePrime(certainty, random, true)) + return; } } } |