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.engines.RC4Engine implements org.bouncycastle.crypto.StreamCipher
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: org.bouncycastle.crypto.engines.RC4Engine
  super_class: java.lang.Object
{
  private static final int STATE_LENGTH;
    descriptor: I
    flags: (0x001a) ACC_PRIVATE, ACC_STATIC, ACC_FINAL
    ConstantValue: 256

  private byte[] engineState;
    descriptor: [B
    flags: (0x0002) ACC_PRIVATE

  private int x;
    descriptor: I
    flags: (0x0002) ACC_PRIVATE

  private int y;
    descriptor: I
    flags: (0x0002) ACC_PRIVATE

  private byte[] workingKey;
    descriptor: [B
    flags: (0x0002) ACC_PRIVATE

  public void <init>();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=1, args_size=1
        start local 0 // org.bouncycastle.crypto.engines.RC4Engine this
         0: .line 8
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 17
            aload 0 /* this */
            aconst_null
            putfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
         2: .line 18
            aload 0 /* this */
            iconst_0
            putfield org.bouncycastle.crypto.engines.RC4Engine.x:I
         3: .line 19
            aload 0 /* this */
            iconst_0
            putfield org.bouncycastle.crypto.engines.RC4Engine.y:I
         4: .line 20
            aload 0 /* this */
            aconst_null
            putfield org.bouncycastle.crypto.engines.RC4Engine.workingKey:[B
         5: .line 8
            return
        end local 0 // org.bouncycastle.crypto.engines.RC4Engine this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    6     0  this  Lorg/bouncycastle/crypto/engines/RC4Engine;

  public void init(boolean, org.bouncycastle.crypto.CipherParameters);
    descriptor: (ZLorg/bouncycastle/crypto/CipherParameters;)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=3, args_size=3
        start local 0 // org.bouncycastle.crypto.engines.RC4Engine this
        start local 1 // boolean forEncryption
        start local 2 // org.bouncycastle.crypto.CipherParameters params
         0: .line 35
            aload 2 /* params */
            instanceof org.bouncycastle.crypto.params.KeyParameter
            ifeq 4
         1: .line 42
            aload 0 /* this */
            aload 2 /* params */
            checkcast org.bouncycastle.crypto.params.KeyParameter
            invokevirtual org.bouncycastle.crypto.params.KeyParameter.getKey:()[B
            putfield org.bouncycastle.crypto.engines.RC4Engine.workingKey:[B
         2: .line 43
            aload 0 /* this */
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.workingKey:[B
            invokevirtual org.bouncycastle.crypto.engines.RC4Engine.setKey:([B)V
         3: .line 45
            return
         4: .line 48
      StackMap locals:
      StackMap stack:
            new java.lang.IllegalArgumentException
            dup
            new java.lang.StringBuilder
            dup
            ldc "invalid parameter passed to RC4 init - "
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            aload 2 /* params */
            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.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
        end local 2 // org.bouncycastle.crypto.CipherParameters params
        end local 1 // boolean forEncryption
        end local 0 // org.bouncycastle.crypto.engines.RC4Engine this
      LocalVariableTable:
        Start  End  Slot           Name  Signature
            0    5     0           this  Lorg/bouncycastle/crypto/engines/RC4Engine;
            0    5     1  forEncryption  Z
            0    5     2         params  Lorg/bouncycastle/crypto/CipherParameters;
    MethodParameters:
               Name  Flags
      forEncryption  
      params         

  public java.lang.String getAlgorithmName();
    descriptor: ()Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.bouncycastle.crypto.engines.RC4Engine this
         0: .line 53
            ldc "RC4"
            areturn
        end local 0 // org.bouncycastle.crypto.engines.RC4Engine this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/bouncycastle/crypto/engines/RC4Engine;

  public byte returnByte(byte);
    descriptor: (B)B
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=3, args_size=2
        start local 0 // org.bouncycastle.crypto.engines.RC4Engine this
        start local 1 // byte in
         0: .line 58
            aload 0 /* this */
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            iconst_1
            iadd
            sipush 255
            iand
            putfield org.bouncycastle.crypto.engines.RC4Engine.x:I
         1: .line 59
            aload 0 /* this */
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            baload
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.y:I
            iadd
            sipush 255
            iand
            putfield org.bouncycastle.crypto.engines.RC4Engine.y:I
         2: .line 62
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            baload
            istore 2 /* tmp */
        start local 2 // byte tmp
         3: .line 63
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.y:I
            baload
            bastore
         4: .line 64
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.y:I
            iload 2 /* tmp */
            bastore
         5: .line 67
            iload 1 /* in */
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            baload
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.y:I
            baload
            iadd
            sipush 255
            iand
            baload
            ixor
            i2b
            ireturn
        end local 2 // byte tmp
        end local 1 // byte in
        end local 0 // org.bouncycastle.crypto.engines.RC4Engine this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    6     0  this  Lorg/bouncycastle/crypto/engines/RC4Engine;
            0    6     1    in  B
            3    6     2   tmp  B
    MethodParameters:
      Name  Flags
      in    

  public void processBytes(byte[], int, int, byte[], int);
    descriptor: ([BII[BI)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=7, locals=8, args_size=6
        start local 0 // org.bouncycastle.crypto.engines.RC4Engine this
        start local 1 // byte[] in
        start local 2 // int inOff
        start local 3 // int len
        start local 4 // byte[] out
        start local 5 // int outOff
         0: .line 77
            iload 2 /* inOff */
            iload 3 /* len */
            iadd
            aload 1 /* in */
            arraylength
            if_icmple 2
         1: .line 79
            new org.bouncycastle.crypto.DataLengthException
            dup
            ldc "input buffer too short"
            invokespecial org.bouncycastle.crypto.DataLengthException.<init>:(Ljava/lang/String;)V
            athrow
         2: .line 82
      StackMap locals:
      StackMap stack:
            iload 5 /* outOff */
            iload 3 /* len */
            iadd
            aload 4 /* out */
            arraylength
            if_icmple 4
         3: .line 84
            new org.bouncycastle.crypto.DataLengthException
            dup
            ldc "output buffer too short"
            invokespecial org.bouncycastle.crypto.DataLengthException.<init>:(Ljava/lang/String;)V
            athrow
         4: .line 87
      StackMap locals:
      StackMap stack:
            iconst_0
            istore 6 /* i */
        start local 6 // int i
         5: goto 15
         6: .line 89
      StackMap locals: int
      StackMap stack:
            aload 0 /* this */
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            iconst_1
            iadd
            sipush 255
            iand
            putfield org.bouncycastle.crypto.engines.RC4Engine.x:I
         7: .line 90
            aload 0 /* this */
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            baload
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.y:I
            iadd
            sipush 255
            iand
            putfield org.bouncycastle.crypto.engines.RC4Engine.y:I
         8: .line 93
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            baload
            istore 7 /* tmp */
        start local 7 // byte tmp
         9: .line 94
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.y:I
            baload
            bastore
        10: .line 95
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.y:I
            iload 7 /* tmp */
            bastore
        11: .line 98
            aload 4 /* out */
            iload 6 /* i */
            iload 5 /* outOff */
            iadd
            aload 1 /* in */
            iload 6 /* i */
            iload 2 /* inOff */
            iadd
            baload
        12: .line 99
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.x:I
            baload
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.y:I
            baload
            iadd
            sipush 255
            iand
            baload
            ixor
            i2b
        13: .line 98
            bastore
        end local 7 // byte tmp
        14: .line 87
            iinc 6 /* i */ 1
      StackMap locals:
      StackMap stack:
        15: iload 6 /* i */
            iload 3 /* len */
            if_icmplt 6
        end local 6 // int i
        16: .line 101
            return
        end local 5 // int outOff
        end local 4 // byte[] out
        end local 3 // int len
        end local 2 // int inOff
        end local 1 // byte[] in
        end local 0 // org.bouncycastle.crypto.engines.RC4Engine this
      LocalVariableTable:
        Start  End  Slot    Name  Signature
            0   17     0    this  Lorg/bouncycastle/crypto/engines/RC4Engine;
            0   17     1      in  [B
            0   17     2   inOff  I
            0   17     3     len  I
            0   17     4     out  [B
            0   17     5  outOff  I
            5   16     6       i  I
            9   14     7     tmp  B
    MethodParameters:
        Name  Flags
      in      
      inOff   
      len     
      out     
      outOff  

  public void reset();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=1, args_size=1
        start local 0 // org.bouncycastle.crypto.engines.RC4Engine this
         0: .line 105
            aload 0 /* this */
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.workingKey:[B
            invokevirtual org.bouncycastle.crypto.engines.RC4Engine.setKey:([B)V
         1: .line 106
            return
        end local 0 // org.bouncycastle.crypto.engines.RC4Engine this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    2     0  this  Lorg/bouncycastle/crypto/engines/RC4Engine;

  private void setKey(byte[]);
    descriptor: ([B)V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=4, locals=6, args_size=2
        start local 0 // org.bouncycastle.crypto.engines.RC4Engine this
        start local 1 // byte[] keyBytes
         0: .line 112
            aload 0 /* this */
            aload 1 /* keyBytes */
            putfield org.bouncycastle.crypto.engines.RC4Engine.workingKey:[B
         1: .line 116
            aload 0 /* this */
            iconst_0
            putfield org.bouncycastle.crypto.engines.RC4Engine.x:I
         2: .line 117
            aload 0 /* this */
            iconst_0
            putfield org.bouncycastle.crypto.engines.RC4Engine.y:I
         3: .line 119
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            ifnonnull 5
         4: .line 121
            aload 0 /* this */
            sipush 256
            newarray 8
            putfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
         5: .line 125
      StackMap locals:
      StackMap stack:
            iconst_0
            istore 2 /* i */
        start local 2 // int i
         6: goto 9
         7: .line 127
      StackMap locals: int
      StackMap stack:
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            iload 2 /* i */
            iload 2 /* i */
            i2b
            bastore
         8: .line 125
            iinc 2 /* i */ 1
      StackMap locals:
      StackMap stack:
         9: iload 2 /* i */
            sipush 256
            if_icmplt 7
        end local 2 // int i
        10: .line 130
            iconst_0
            istore 2 /* i1 */
        start local 2 // int i1
        11: .line 131
            iconst_0
            istore 3 /* i2 */
        start local 3 // int i2
        12: .line 133
            iconst_0
            istore 4 /* i */
        start local 4 // int i
        13: goto 20
        14: .line 135
      StackMap locals: int int
      StackMap stack:
            aload 1 /* keyBytes */
            iload 2 /* i1 */
            baload
            sipush 255
            iand
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            iload 4 /* i */
            baload
            iadd
            iload 3 /* i2 */
            iadd
            sipush 255
            iand
            istore 3 /* i2 */
        15: .line 137
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            iload 4 /* i */
            baload
            istore 5 /* tmp */
        start local 5 // byte tmp
        16: .line 138
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            iload 4 /* i */
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            iload 3 /* i2 */
            baload
            bastore
        17: .line 139
            aload 0 /* this */
            getfield org.bouncycastle.crypto.engines.RC4Engine.engineState:[B
            iload 3 /* i2 */
            iload 5 /* tmp */
            bastore
        18: .line 140
            iload 2 /* i1 */
            iconst_1
            iadd
            aload 1 /* keyBytes */
            arraylength
            irem
            istore 2 /* i1 */
        end local 5 // byte tmp
        19: .line 133
            iinc 4 /* i */ 1
      StackMap locals:
      StackMap stack:
        20: iload 4 /* i */
            sipush 256
            if_icmplt 14
        end local 4 // int i
        21: .line 142
            return
        end local 3 // int i2
        end local 2 // int i1
        end local 1 // byte[] keyBytes
        end local 0 // org.bouncycastle.crypto.engines.RC4Engine this
      LocalVariableTable:
        Start  End  Slot      Name  Signature
            0   22     0      this  Lorg/bouncycastle/crypto/engines/RC4Engine;
            0   22     1  keyBytes  [B
            6   10     2         i  I
           11   22     2        i1  I
           12   22     3        i2  I
           13   21     4         i  I
           16   19     5       tmp  B
    MethodParameters:
          Name  Flags
      keyBytes  
}
SourceFile: "RC4Engine.java"