http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5. 
public class org.bouncycastle.crypto.signers.ECNRSigner implements org.bouncycastle.crypto.DSA
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: org.bouncycastle.crypto.signers.ECNRSigner
  super_class: java.lang.Object
{
  private boolean forSigning;
    descriptor: Z
    flags: (0x0002) ACC_PRIVATE

  private org.bouncycastle.crypto.params.ECKeyParameters key;
    descriptor: Lorg/bouncycastle/crypto/params/ECKeyParameters;
    flags: (0x0002) ACC_PRIVATE

  private java.security.SecureRandom random;
    descriptor: Ljava/security/SecureRandom;
    flags: (0x0002) ACC_PRIVATE

  public void <init>();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.bouncycastle.crypto.signers.ECNRSigner this
         0: .line 23
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // org.bouncycastle.crypto.signers.ECNRSigner this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/bouncycastle/crypto/signers/ECNRSigner;

  public void init(boolean, org.bouncycastle.crypto.CipherParameters);
    descriptor: (ZLorg/bouncycastle/crypto/CipherParameters;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=4, args_size=3
        start local 0 // org.bouncycastle.crypto.signers.ECNRSigner this
        start local 1 // boolean forSigning
        start local 2 // org.bouncycastle.crypto.CipherParameters param
         0: .line 34
            aload 0 /* this */
            iload 1 /* forSigning */
            putfield org.bouncycastle.crypto.signers.ECNRSigner.forSigning:Z
         1: .line 36
            iload 1 /* forSigning */
            ifeq 10
         2: .line 38
            aload 2 /* param */
            instanceof org.bouncycastle.crypto.params.ParametersWithRandom
            ifeq 7
         3: .line 40
            aload 2 /* param */
            checkcast org.bouncycastle.crypto.params.ParametersWithRandom
            astore 3 /* rParam */
        start local 3 // org.bouncycastle.crypto.params.ParametersWithRandom rParam
         4: .line 42
            aload 0 /* this */
            aload 3 /* rParam */
            invokevirtual org.bouncycastle.crypto.params.ParametersWithRandom.getRandom:()Ljava/security/SecureRandom;
            putfield org.bouncycastle.crypto.signers.ECNRSigner.random:Ljava/security/SecureRandom;
         5: .line 43
            aload 0 /* this */
            aload 3 /* rParam */
            invokevirtual org.bouncycastle.crypto.params.ParametersWithRandom.getParameters:()Lorg/bouncycastle/crypto/CipherParameters;
            checkcast org.bouncycastle.crypto.params.ECPrivateKeyParameters
            putfield org.bouncycastle.crypto.signers.ECNRSigner.key:Lorg/bouncycastle/crypto/params/ECKeyParameters;
        end local 3 // org.bouncycastle.crypto.params.ParametersWithRandom rParam
         6: .line 44
            goto 11
         7: .line 47
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            new java.security.SecureRandom
            dup
            invokespecial java.security.SecureRandom.<init>:()V
            putfield org.bouncycastle.crypto.signers.ECNRSigner.random:Ljava/security/SecureRandom;
         8: .line 48
            aload 0 /* this */
            aload 2 /* param */
            checkcast org.bouncycastle.crypto.params.ECPrivateKeyParameters
            putfield org.bouncycastle.crypto.signers.ECNRSigner.key:Lorg/bouncycastle/crypto/params/ECKeyParameters;
         9: .line 50
            goto 11
        10: .line 53
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            aload 2 /* param */
            checkcast org.bouncycastle.crypto.params.ECPublicKeyParameters
            putfield org.bouncycastle.crypto.signers.ECNRSigner.key:Lorg/bouncycastle/crypto/params/ECKeyParameters;
        11: .line 55
      StackMap locals:
      StackMap stack:
            return
        end local 2 // org.bouncycastle.crypto.CipherParameters param
        end local 1 // boolean forSigning
        end local 0 // org.bouncycastle.crypto.signers.ECNRSigner this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0   12     0        this  Lorg/bouncycastle/crypto/signers/ECNRSigner;
            0   12     1  forSigning  Z
            0   12     2       param  Lorg/bouncycastle/crypto/CipherParameters;
            4    6     3      rParam  Lorg/bouncycastle/crypto/params/ParametersWithRandom;
    MethodParameters:
            Name  Flags
      forSigning  
      param       

  public java.math.BigInteger[] generateSignature(byte[]);
    descriptor: ([B)[Ljava/math/BigInteger;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=13, args_size=2
        start local 0 // org.bouncycastle.crypto.signers.ECNRSigner this
        start local 1 // byte[] digest
         0: .line 70
            aload 0 /* this */
            getfield org.bouncycastle.crypto.signers.ECNRSigner.forSigning:Z
            ifne 2
         1: .line 72
            new java.lang.IllegalStateException
            dup
            ldc "not initialised for signing"
            invokespecial java.lang.IllegalStateException.<init>:(Ljava/lang/String;)V
            athrow
         2: .line 75
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield org.bouncycastle.crypto.signers.ECNRSigner.key:Lorg/bouncycastle/crypto/params/ECKeyParameters;
            checkcast org.bouncycastle.crypto.params.ECPrivateKeyParameters
            invokevirtual org.bouncycastle.crypto.params.ECPrivateKeyParameters.getParameters:()Lorg/bouncycastle/crypto/params/ECDomainParameters;
            invokevirtual org.bouncycastle.crypto.params.ECDomainParameters.getN:()Ljava/math/BigInteger;
            astore 2 /* n */
        start local 2 // java.math.BigInteger n
         3: .line 76
            aload 2 /* n */
            invokevirtual java.math.BigInteger.bitLength:()I
            istore 3 /* nBitLength */
        start local 3 // int nBitLength
         4: .line 78
            new java.math.BigInteger
            dup
            iconst_1
            aload 1 /* digest */
            invokespecial java.math.BigInteger.<init>:(I[B)V
            astore 4 /* e */
        start local 4 // java.math.BigInteger e
         5: .line 79
            aload 4 /* e */
            invokevirtual java.math.BigInteger.bitLength:()I
            istore 5 /* eBitLength */
        start local 5 // int eBitLength
         6: .line 81
            aload 0 /* this */
            getfield org.bouncycastle.crypto.signers.ECNRSigner.key:Lorg/bouncycastle/crypto/params/ECKeyParameters;
            checkcast org.bouncycastle.crypto.params.ECPrivateKeyParameters
            astore 6 /* privKey */
        start local 6 // org.bouncycastle.crypto.params.ECPrivateKeyParameters privKey
         7: .line 83
            iload 5 /* eBitLength */
            iload 3 /* nBitLength */
            if_icmple 9
         8: .line 85
            new org.bouncycastle.crypto.DataLengthException
            dup
            ldc "input too large for ECNR key."
            invokespecial org.bouncycastle.crypto.DataLengthException.<init>:(Ljava/lang/String;)V
            athrow
         9: .line 88
      StackMap locals: org.bouncycastle.crypto.signers.ECNRSigner byte[] java.math.BigInteger int java.math.BigInteger int org.bouncycastle.crypto.params.ECPrivateKeyParameters
      StackMap stack:
            aconst_null
            astore 7 /* r */
        start local 7 // java.math.BigInteger r
        10: .line 89
            aconst_null
            astore 8 /* s */
        start local 8 // java.math.BigInteger s
        11: .line 96
      StackMap locals: java.math.BigInteger java.math.BigInteger
      StackMap stack:
            new org.bouncycastle.crypto.generators.ECKeyPairGenerator
            dup
            invokespecial org.bouncycastle.crypto.generators.ECKeyPairGenerator.<init>:()V
            astore 10 /* keyGen */
        start local 10 // org.bouncycastle.crypto.generators.ECKeyPairGenerator keyGen
        12: .line 98
            aload 10 /* keyGen */
            new org.bouncycastle.crypto.params.ECKeyGenerationParameters
            dup
            aload 6 /* privKey */
            invokevirtual org.bouncycastle.crypto.params.ECPrivateKeyParameters.getParameters:()Lorg/bouncycastle/crypto/params/ECDomainParameters;
            aload 0 /* this */
            getfield org.bouncycastle.crypto.signers.ECNRSigner.random:Ljava/security/SecureRandom;
            invokespecial org.bouncycastle.crypto.params.ECKeyGenerationParameters.<init>:(Lorg/bouncycastle/crypto/params/ECDomainParameters;Ljava/security/SecureRandom;)V
            invokevirtual org.bouncycastle.crypto.generators.ECKeyPairGenerator.init:(Lorg/bouncycastle/crypto/KeyGenerationParameters;)V
        13: .line 100
            aload 10 /* keyGen */
            invokevirtual org.bouncycastle.crypto.generators.ECKeyPairGenerator.generateKeyPair:()Lorg/bouncycastle/crypto/AsymmetricCipherKeyPair;
            astore 9 /* tempPair */
        start local 9 // org.bouncycastle.crypto.AsymmetricCipherKeyPair tempPair
        14: .line 103
            aload 9 /* tempPair */
            invokevirtual org.bouncycastle.crypto.AsymmetricCipherKeyPair.getPublic:()Lorg/bouncycastle/crypto/CipherParameters;
            checkcast org.bouncycastle.crypto.params.ECPublicKeyParameters
            astore 11 /* V */
        start local 11 // org.bouncycastle.crypto.params.ECPublicKeyParameters V
        15: .line 104
            aload 11 /* V */
            invokevirtual org.bouncycastle.crypto.params.ECPublicKeyParameters.getQ:()Lorg/bouncycastle/math/ec/ECPoint;
            invokevirtual org.bouncycastle.math.ec.ECPoint.getX:()Lorg/bouncycastle/math/ec/ECFieldElement;
            invokevirtual org.bouncycastle.math.ec.ECFieldElement.toBigInteger:()Ljava/math/BigInteger;
            astore 12 /* Vx */
        start local 12 // java.math.BigInteger Vx
        16: .line 106
            aload 12 /* Vx */
            aload 4 /* e */
            invokevirtual java.math.BigInteger.add:(Ljava/math/BigInteger;)Ljava/math/BigInteger;
            aload 2 /* n */
            invokevirtual java.math.BigInteger.mod:(Ljava/math/BigInteger;)Ljava/math/BigInteger;
            astore 7 /* r */
        end local 12 // java.math.BigInteger Vx
        end local 11 // org.bouncycastle.crypto.params.ECPublicKeyParameters V
        end local 10 // org.bouncycastle.crypto.generators.ECKeyPairGenerator keyGen
        17: .line 108
            aload 7 /* r */
            getstatic org.bouncycastle.math.ec.ECConstants.ZERO:Ljava/math/BigInteger;
            invokevirtual java.math.BigInteger.equals:(Ljava/lang/Object;)Z
            ifne 11
        18: .line 111
            aload 6 /* privKey */
            invokevirtual org.bouncycastle.crypto.params.ECPrivateKeyParameters.getD:()Ljava/math/BigInteger;
            astore 10 /* x */
        start local 10 // java.math.BigInteger x
        19: .line 112
            aload 9 /* tempPair */
            invokevirtual org.bouncycastle.crypto.AsymmetricCipherKeyPair.getPrivate:()Lorg/bouncycastle/crypto/CipherParameters;
            checkcast org.bouncycastle.crypto.params.ECPrivateKeyParameters
            invokevirtual org.bouncycastle.crypto.params.ECPrivateKeyParameters.getD:()Ljava/math/BigInteger;
            astore 11 /* u */
        start local 11 // java.math.BigInteger u
        20: .line 113
            aload 11 /* u */
            aload 7 /* r */
            aload 10 /* x */
            invokevirtual java.math.BigInteger.multiply:(Ljava/math/BigInteger;)Ljava/math/BigInteger;
            invokevirtual java.math.BigInteger.subtract:(Ljava/math/BigInteger;)Ljava/math/BigInteger;
            aload 2 /* n */
            invokevirtual java.math.BigInteger.mod:(Ljava/math/BigInteger;)Ljava/math/BigInteger;
            astore 8 /* s */
        21: .line 115
            iconst_2
            anewarray java.math.BigInteger
            astore 12 /* res */
        start local 12 // java.math.BigInteger[] res
        22: .line 116
            aload 12 /* res */
            iconst_0
            aload 7 /* r */
            aastore
        23: .line 117
            aload 12 /* res */
            iconst_1
            aload 8 /* s */
            aastore
        24: .line 119
            aload 12 /* res */
            areturn
        end local 12 // java.math.BigInteger[] res
        end local 11 // java.math.BigInteger u
        end local 10 // java.math.BigInteger x
        end local 9 // org.bouncycastle.crypto.AsymmetricCipherKeyPair tempPair
        end local 8 // java.math.BigInteger s
        end local 7 // java.math.BigInteger r
        end local 6 // org.bouncycastle.crypto.params.ECPrivateKeyParameters privKey
        end local 5 // int eBitLength
        end local 4 // java.math.BigInteger e
        end local 3 // int nBitLength
        end local 2 // java.math.BigInteger n
        end local 1 // byte[] digest
        end local 0 // org.bouncycastle.crypto.signers.ECNRSigner this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0   25     0        this  Lorg/bouncycastle/crypto/signers/ECNRSigner;
            0   25     1      digest  [B
            3   25     2           n  Ljava/math/BigInteger;
            4   25     3  nBitLength  I
            5   25     4           e  Ljava/math/BigInteger;
            6   25     5  eBitLength  I
            7   25     6     privKey  Lorg/bouncycastle/crypto/params/ECPrivateKeyParameters;
           10   25     7           r  Ljava/math/BigInteger;
           11   25     8           s  Ljava/math/BigInteger;
           14   25     9    tempPair  Lorg/bouncycastle/crypto/AsymmetricCipherKeyPair;
           12   17    10      keyGen  Lorg/bouncycastle/crypto/generators/ECKeyPairGenerator;
           15   17    11           V  Lorg/bouncycastle/crypto/params/ECPublicKeyParameters;
           16   17    12          Vx  Ljava/math/BigInteger;
           19   25    10           x  Ljava/math/BigInteger;
           20   25    11           u  Ljava/math/BigInteger;
           22   25    12         res  [Ljava/math/BigInteger;
    MethodParameters:
        Name  Flags
      digest  

  public boolean verifySignature(byte[], java.math.BigInteger, java.math.BigInteger);
    descriptor: ([BLjava/math/BigInteger;Ljava/math/BigInteger;)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=14, args_size=4
        start local 0 // org.bouncycastle.crypto.signers.ECNRSigner this
        start local 1 // byte[] digest
        start local 2 // java.math.BigInteger r
        start local 3 // java.math.BigInteger s
         0: .line 141
            aload 0 /* this */
            getfield org.bouncycastle.crypto.signers.ECNRSigner.forSigning:Z
            ifeq 2
         1: .line 143
            new java.lang.IllegalStateException
            dup
            ldc "not initialised for verifying"
            invokespecial java.lang.IllegalStateException.<init>:(Ljava/lang/String;)V
            athrow
         2: .line 146
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            getfield org.bouncycastle.crypto.signers.ECNRSigner.key:Lorg/bouncycastle/crypto/params/ECKeyParameters;
            checkcast org.bouncycastle.crypto.params.ECPublicKeyParameters
            astore 4 /* pubKey */
        start local 4 // org.bouncycastle.crypto.params.ECPublicKeyParameters pubKey
         3: .line 147
            aload 4 /* pubKey */
            invokevirtual org.bouncycastle.crypto.params.ECPublicKeyParameters.getParameters:()Lorg/bouncycastle/crypto/params/ECDomainParameters;
            invokevirtual org.bouncycastle.crypto.params.ECDomainParameters.getN:()Ljava/math/BigInteger;
            astore 5 /* n */
        start local 5 // java.math.BigInteger n
         4: .line 148
            aload 5 /* n */
            invokevirtual java.math.BigInteger.bitLength:()I
            istore 6 /* nBitLength */
        start local 6 // int nBitLength
         5: .line 150
            new java.math.BigInteger
            dup
            iconst_1
            aload 1 /* digest */
            invokespecial java.math.BigInteger.<init>:(I[B)V
            astore 7 /* e */
        start local 7 // java.math.BigInteger e
         6: .line 151
            aload 7 /* e */
            invokevirtual java.math.BigInteger.bitLength:()I
            istore 8 /* eBitLength */
        start local 8 // int eBitLength
         7: .line 153
            iload 8 /* eBitLength */
            iload 6 /* nBitLength */
            if_icmple 9
         8: .line 155
            new org.bouncycastle.crypto.DataLengthException
            dup
            ldc "input too large for ECNR key."
            invokespecial org.bouncycastle.crypto.DataLengthException.<init>:(Ljava/lang/String;)V
            athrow
         9: .line 159
      StackMap locals: org.bouncycastle.crypto.signers.ECNRSigner byte[] java.math.BigInteger java.math.BigInteger org.bouncycastle.crypto.params.ECPublicKeyParameters java.math.BigInteger int java.math.BigInteger int
      StackMap stack:
            aload 2 /* r */
            getstatic org.bouncycastle.math.ec.ECConstants.ONE:Ljava/math/BigInteger;
            invokevirtual java.math.BigInteger.compareTo:(Ljava/math/BigInteger;)I
            iflt 10
            aload 2 /* r */
            aload 5 /* n */
            invokevirtual java.math.BigInteger.compareTo:(Ljava/math/BigInteger;)I
            iflt 11
        10: .line 161
      StackMap locals:
      StackMap stack:
            iconst_0
            ireturn
        11: .line 165
      StackMap locals:
      StackMap stack:
            aload 3 /* s */
            getstatic org.bouncycastle.math.ec.ECConstants.ZERO:Ljava/math/BigInteger;
            invokevirtual java.math.BigInteger.compareTo:(Ljava/math/BigInteger;)I
            iflt 12
            aload 3 /* s */
            aload 5 /* n */
            invokevirtual java.math.BigInteger.compareTo:(Ljava/math/BigInteger;)I
            iflt 13
        12: .line 167
      StackMap locals:
      StackMap stack:
            iconst_0
            ireturn
        13: .line 172
      StackMap locals:
      StackMap stack:
            aload 4 /* pubKey */
            invokevirtual org.bouncycastle.crypto.params.ECPublicKeyParameters.getParameters:()Lorg/bouncycastle/crypto/params/ECDomainParameters;
            invokevirtual org.bouncycastle.crypto.params.ECDomainParameters.getG:()Lorg/bouncycastle/math/ec/ECPoint;
            astore 9 /* G */
        start local 9 // org.bouncycastle.math.ec.ECPoint G
        14: .line 173
            aload 4 /* pubKey */
            invokevirtual org.bouncycastle.crypto.params.ECPublicKeyParameters.getQ:()Lorg/bouncycastle/math/ec/ECPoint;
            astore 10 /* W */
        start local 10 // org.bouncycastle.math.ec.ECPoint W
        15: .line 175
            aload 9 /* G */
            aload 3 /* s */
            aload 10 /* W */
            aload 2 /* r */
            invokestatic org.bouncycastle.math.ec.ECAlgorithms.sumOfTwoMultiplies:(Lorg/bouncycastle/math/ec/ECPoint;Ljava/math/BigInteger;Lorg/bouncycastle/math/ec/ECPoint;Ljava/math/BigInteger;)Lorg/bouncycastle/math/ec/ECPoint;
            astore 11 /* P */
        start local 11 // org.bouncycastle.math.ec.ECPoint P
        16: .line 177
            aload 11 /* P */
            invokevirtual org.bouncycastle.math.ec.ECPoint.getX:()Lorg/bouncycastle/math/ec/ECFieldElement;
            invokevirtual org.bouncycastle.math.ec.ECFieldElement.toBigInteger:()Ljava/math/BigInteger;
            astore 12 /* x */
        start local 12 // java.math.BigInteger x
        17: .line 178
            aload 2 /* r */
            aload 12 /* x */
            invokevirtual java.math.BigInteger.subtract:(Ljava/math/BigInteger;)Ljava/math/BigInteger;
            aload 5 /* n */
            invokevirtual java.math.BigInteger.mod:(Ljava/math/BigInteger;)Ljava/math/BigInteger;
            astore 13 /* t */
        start local 13 // java.math.BigInteger t
        18: .line 180
            aload 13 /* t */
            aload 7 /* e */
            invokevirtual java.math.BigInteger.equals:(Ljava/lang/Object;)Z
            ireturn
        end local 13 // java.math.BigInteger t
        end local 12 // java.math.BigInteger x
        end local 11 // org.bouncycastle.math.ec.ECPoint P
        end local 10 // org.bouncycastle.math.ec.ECPoint W
        end local 9 // org.bouncycastle.math.ec.ECPoint G
        end local 8 // int eBitLength
        end local 7 // java.math.BigInteger e
        end local 6 // int nBitLength
        end local 5 // java.math.BigInteger n
        end local 4 // org.bouncycastle.crypto.params.ECPublicKeyParameters pubKey
        end local 3 // java.math.BigInteger s
        end local 2 // java.math.BigInteger r
        end local 1 // byte[] digest
        end local 0 // org.bouncycastle.crypto.signers.ECNRSigner this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0   19     0        this  Lorg/bouncycastle/crypto/signers/ECNRSigner;
            0   19     1      digest  [B
            0   19     2           r  Ljava/math/BigInteger;
            0   19     3           s  Ljava/math/BigInteger;
            3   19     4      pubKey  Lorg/bouncycastle/crypto/params/ECPublicKeyParameters;
            4   19     5           n  Ljava/math/BigInteger;
            5   19     6  nBitLength  I
            6   19     7           e  Ljava/math/BigInteger;
            7   19     8  eBitLength  I
           14   19     9           G  Lorg/bouncycastle/math/ec/ECPoint;
           15   19    10           W  Lorg/bouncycastle/math/ec/ECPoint;
           16   19    11           P  Lorg/bouncycastle/math/ec/ECPoint;
           17   19    12           x  Ljava/math/BigInteger;
           18   19    13           t  Ljava/math/BigInteger;
    MethodParameters:
        Name  Flags
      digest  
      r       
      s       
}
SourceFile: "ECNRSigner.java"