The XOR Surface

XOR Makes Ciphertext

The ciphertext is recomputed byte by byte as plaintext XOR keystream.

highlighted = computed this step

XOR makes the ciphertext

For this toy, ciphertext equals plaintext XOR keystream. The table recomputes the ciphertext row from the pinned inputs.

ciphertext=0x7f7f54017a6a\text{ciphertext}=0x7f7f54017a6a
Ciphertext is XORToy XOR encryption and decryption are recomputed from pinned bytes.Plaintext48 bits / 6 bytes0x7061793d3130byte 0byte 1byte 2byte 301110000011000010111100100111101byte 4byte 50011000100110000byte-00x70byte-10x61byte-20x79byte-30x3dbyte-40x31byte-50x30Keystream48 bits / 6 bytes0x0f1e2d3c4b5abyte 0byte 1byte 2byte 300001111000111100010110100111100byte 4byte 50100101101011010byte-00x0fbyte-10x1ebyte-20x2dbyte-30x3cbyte-40x4bbyte-50x5aCiphertext48 bits / 6 bytes0x7f7f54017a6abyte 0byte 1byte 2byte 301111111011111110101010000000001byte 4byte 50111101001101010byte-00x7fbyte-10x7fbyte-20x54byte-30x01byte-40x7abyte-50x6aToy XOR rows - changed byte 4rowvaluecheckplaintext7061793d3130pinned byteskeystream0f1e2d3c4b5apinned bytesciphertext7f7f54017a6aplaintext xor keystreamtarget plaintext7061793d3930attacker targetattack mask000000000800plaintext xor targetmodified ciphertext7f7f5401726aciphertext xor maskdecrypted modified7061793d3930modified ciphertext xor keystream

Read the ciphertext row

The recomputed ciphertext is 0x7f7f54017a6a.

ciphertext=0x7f7f54017a6a\text{ciphertext}=0x7f7f54017a6a
Ciphertext is XORToy XOR encryption and decryption are recomputed from pinned bytes.Plaintext48 bits / 6 bytes0x7061793d3130byte 0byte 1byte 2byte 301110000011000010111100100111101byte 4byte 50011000100110000byte-00x70byte-10x61byte-20x79byte-30x3dbyte-40x31byte-50x30Keystream48 bits / 6 bytes0x0f1e2d3c4b5abyte 0byte 1byte 2byte 300001111000111100010110100111100byte 4byte 50100101101011010byte-00x0fbyte-10x1ebyte-20x2dbyte-30x3cbyte-40x4bbyte-50x5aCiphertext48 bits / 6 bytes0x7f7f54017a6abyte 0byte 1byte 2byte 301111111011111110101010000000001byte 4byte 50111101001101010byte-00x7fbyte-10x7fbyte-20x54byte-30x01byte-40x7abyte-50x6aToy XOR rows - changed byte 4rowvaluecheckplaintext7061793d3130pinned byteskeystream0f1e2d3c4b5apinned bytesciphertext7f7f54017a6aplaintext xor keystreamtarget plaintext7061793d3930attacker targetattack mask000000000800plaintext xor targetmodified ciphertext7f7f5401726aciphertext xor maskdecrypted modified7061793d3930modified ciphertext xor keystream

The same rule applies byte by byte

Each ciphertext byte is one plaintext byte XOR one keystream byte. The table rejects a row that does not match that byte rule.

xor byte rule=1\text{xor byte rule}=1
Ciphertext is XORToy XOR encryption and decryption are recomputed from pinned bytes.Plaintext48 bits / 6 bytes0x7061793d3130byte 0byte 1byte 2byte 301110000011000010111100100111101byte 4byte 50011000100110000byte-00x70byte-10x61byte-20x79byte-30x3dbyte-40x31byte-50x30Keystream48 bits / 6 bytes0x0f1e2d3c4b5abyte 0byte 1byte 2byte 300001111000111100010110100111100byte 4byte 50100101101011010byte-00x0fbyte-10x1ebyte-20x2dbyte-30x3cbyte-40x4bbyte-50x5aCiphertext48 bits / 6 bytes0x7f7f54017a6abyte 0byte 1byte 2byte 301111111011111110101010000000001byte 4byte 50111101001101010byte-00x7fbyte-10x7fbyte-20x54byte-30x01byte-40x7abyte-50x6aToy XOR rows - changed byte 4rowvaluecheckplaintext7061793d3130pinned byteskeystream0f1e2d3c4b5apinned bytesciphertext7f7f54017a6aplaintext xor keystreamtarget plaintext7061793d3930attacker targetattack mask000000000800plaintext xor targetmodified ciphertext7f7f5401726aciphertext xor maskdecrypted modified7061793d3930modified ciphertext xor keystream

Summary

In a toy XOR surface, the ciphertext is controlled by bytewise XOR with the keystream.

computed rows=7\text{computed rows}=7
Ciphertext is XORToy XOR encryption and decryption are recomputed from pinned bytes.Plaintext48 bits / 6 bytes0x7061793d3130byte 0byte 1byte 2byte 301110000011000010111100100111101byte 4byte 50011000100110000byte-00x70byte-10x61byte-20x79byte-30x3dbyte-40x31byte-50x30Keystream48 bits / 6 bytes0x0f1e2d3c4b5abyte 0byte 1byte 2byte 300001111000111100010110100111100byte 4byte 50100101101011010byte-00x0fbyte-10x1ebyte-20x2dbyte-30x3cbyte-40x4bbyte-50x5aCiphertext48 bits / 6 bytes0x7f7f54017a6abyte 0byte 1byte 2byte 301111111011111110101010000000001byte 4byte 50111101001101010byte-00x7fbyte-10x7fbyte-20x54byte-30x01byte-40x7abyte-50x6aToy XOR rows - changed byte 4rowvaluecheckplaintext7061793d3130pinned byteskeystream0f1e2d3c4b5apinned bytesciphertext7f7f54017a6aplaintext xor keystreamtarget plaintext7061793d3930attacker targetattack mask000000000800plaintext xor targetmodified ciphertext7f7f5401726aciphertext xor maskdecrypted modified7061793d3930modified ciphertext xor keystream