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.jce.provider.GOST3410Util
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: org.bouncycastle.jce.provider.GOST3410Util
  super_class: java.lang.Object
{
  public void <init>();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.bouncycastle.jce.provider.GOST3410Util this
         0: .line 19
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // org.bouncycastle.jce.provider.GOST3410Util this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/bouncycastle/jce/provider/GOST3410Util;

  public static org.bouncycastle.crypto.params.AsymmetricKeyParameter generatePublicKeyParameter(java.security.PublicKey);
    descriptor: (Ljava/security/PublicKey;)Lorg/bouncycastle/crypto/params/AsymmetricKeyParameter;
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=8, locals=3, args_size=1
        start local 0 // java.security.PublicKey key
         0: .line 25
            aload 0 /* key */
            instanceof org.bouncycastle.jce.interfaces.GOST3410PublicKey
            ifeq 6
         1: .line 27
            aload 0 /* key */
            checkcast org.bouncycastle.jce.interfaces.GOST3410PublicKey
            astore 1 /* k */
        start local 1 // org.bouncycastle.jce.interfaces.GOST3410PublicKey k
         2: .line 28
            aload 1 /* k */
            invokeinterface org.bouncycastle.jce.interfaces.GOST3410PublicKey.getParameters:()Lorg/bouncycastle/jce/interfaces/GOST3410Params;
            invokeinterface org.bouncycastle.jce.interfaces.GOST3410Params.getPublicKeyParameters:()Lorg/bouncycastle/jce/spec/GOST3410PublicKeyParameterSetSpec;
            astore 2 /* p */
        start local 2 // org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec p
         3: .line 30
            new org.bouncycastle.crypto.params.GOST3410PublicKeyParameters
            dup
            aload 1 /* k */
            invokeinterface org.bouncycastle.jce.interfaces.GOST3410PublicKey.getY:()Ljava/math/BigInteger;
         4: .line 31
            new org.bouncycastle.crypto.params.GOST3410Parameters
            dup
            aload 2 /* p */
            invokevirtual org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec.getP:()Ljava/math/BigInteger;
            aload 2 /* p */
            invokevirtual org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec.getQ:()Ljava/math/BigInteger;
            aload 2 /* p */
            invokevirtual org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec.getA:()Ljava/math/BigInteger;
            invokespecial org.bouncycastle.crypto.params.GOST3410Parameters.<init>:(Ljava/math/BigInteger;Ljava/math/BigInteger;Ljava/math/BigInteger;)V
         5: .line 30
            invokespecial org.bouncycastle.crypto.params.GOST3410PublicKeyParameters.<init>:(Ljava/math/BigInteger;Lorg/bouncycastle/crypto/params/GOST3410Parameters;)V
            areturn
        end local 2 // org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec p
        end local 1 // org.bouncycastle.jce.interfaces.GOST3410PublicKey k
         6: .line 34
      StackMap locals:
      StackMap stack:
            new java.security.InvalidKeyException
            dup
            new java.lang.StringBuilder
            dup
            ldc "can't identify GOST3410 public key: "
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            aload 0 /* key */
            invokevirtual java.lang.Object.getClass:()Ljava/lang/Class;
            invokevirtual java.lang.Class.getName:()Ljava/lang/String;
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            invokespecial java.security.InvalidKeyException.<init>:(Ljava/lang/String;)V
            athrow
        end local 0 // java.security.PublicKey key
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    7     0   key  Ljava/security/PublicKey;
            2    6     1     k  Lorg/bouncycastle/jce/interfaces/GOST3410PublicKey;
            3    6     2     p  Lorg/bouncycastle/jce/spec/GOST3410PublicKeyParameterSetSpec;
    Exceptions:
      throws java.security.InvalidKeyException
    MethodParameters:
      Name  Flags
      key   

  public static org.bouncycastle.crypto.params.AsymmetricKeyParameter generatePrivateKeyParameter(java.security.PrivateKey);
    descriptor: (Ljava/security/PrivateKey;)Lorg/bouncycastle/crypto/params/AsymmetricKeyParameter;
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=8, locals=3, args_size=1
        start local 0 // java.security.PrivateKey key
         0: .line 41
            aload 0 /* key */
            instanceof org.bouncycastle.jce.interfaces.GOST3410PrivateKey
            ifeq 6
         1: .line 43
            aload 0 /* key */
            checkcast org.bouncycastle.jce.interfaces.GOST3410PrivateKey
            astore 1 /* k */
        start local 1 // org.bouncycastle.jce.interfaces.GOST3410PrivateKey k
         2: .line 44
            aload 1 /* k */
            invokeinterface org.bouncycastle.jce.interfaces.GOST3410PrivateKey.getParameters:()Lorg/bouncycastle/jce/interfaces/GOST3410Params;
            invokeinterface org.bouncycastle.jce.interfaces.GOST3410Params.getPublicKeyParameters:()Lorg/bouncycastle/jce/spec/GOST3410PublicKeyParameterSetSpec;
            astore 2 /* p */
        start local 2 // org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec p
         3: .line 46
            new org.bouncycastle.crypto.params.GOST3410PrivateKeyParameters
            dup
            aload 1 /* k */
            invokeinterface org.bouncycastle.jce.interfaces.GOST3410PrivateKey.getX:()Ljava/math/BigInteger;
         4: .line 47
            new org.bouncycastle.crypto.params.GOST3410Parameters
            dup
            aload 2 /* p */
            invokevirtual org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec.getP:()Ljava/math/BigInteger;
            aload 2 /* p */
            invokevirtual org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec.getQ:()Ljava/math/BigInteger;
            aload 2 /* p */
            invokevirtual org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec.getA:()Ljava/math/BigInteger;
            invokespecial org.bouncycastle.crypto.params.GOST3410Parameters.<init>:(Ljava/math/BigInteger;Ljava/math/BigInteger;Ljava/math/BigInteger;)V
         5: .line 46
            invokespecial org.bouncycastle.crypto.params.GOST3410PrivateKeyParameters.<init>:(Ljava/math/BigInteger;Lorg/bouncycastle/crypto/params/GOST3410Parameters;)V
            areturn
        end local 2 // org.bouncycastle.jce.spec.GOST3410PublicKeyParameterSetSpec p
        end local 1 // org.bouncycastle.jce.interfaces.GOST3410PrivateKey k
         6: .line 50
      StackMap locals:
      StackMap stack:
            new java.security.InvalidKeyException
            dup
            ldc "can't identify GOST3410 private key."
            invokespecial java.security.InvalidKeyException.<init>:(Ljava/lang/String;)V
            athrow
        end local 0 // java.security.PrivateKey key
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    7     0   key  Ljava/security/PrivateKey;
            2    6     1     k  Lorg/bouncycastle/jce/interfaces/GOST3410PrivateKey;
            3    6     2     p  Lorg/bouncycastle/jce/spec/GOST3410PublicKeyParameterSetSpec;
    Exceptions:
      throws java.security.InvalidKeyException
    MethodParameters:
      Name  Flags
      key   
}
SourceFile: "GOST3410Util.java"