Same Keystream

Second Ciphertext

The second ciphertext uses the same toy keystream again.

highlighted = computed this step

Second plaintext uses the same keystream

Plaintext B is 0x7061793d3930. The keystream row is unchanged.

plaintext B=0x7061793d3930\text{plaintext B}=0x7061793d3930
Second ciphertextCiphertext is recomputed as plaintext XOR the reused toy keystream.Plaintext B48 bits / 6 bytes0x7061793d3930byte 0byte 1byte 2byte 301110000011000010111100100111101byte 4byte 50011100100110000byte-00x70byte-10x61byte-20x79byte-30x3dbyte-40x39byte-50x30Toy keystream48 bits / 6 bytes0x0f1e2d3c4b5abyte 0byte 1byte 2byte 300001111000111100010110100111100byte 4byte 50100101101011010byte-00x0fbyte-10x1ebyte-20x2dbyte-30x3cbyte-40x4bbyte-50x5aCiphertext B48 bits / 6 bytes0x7f7f5401726abyte 0byte 1byte 2byte 301111111011111110101010000000001byte 4byte 50111001001101010byte-00x7fbyte-10x7fbyte-20x54byte-30x01byte-40x72byte-50x6a

Ciphertext B is recomputed

Plaintext B XOR the same toy keystream gives ciphertext B 0x7f7f5401726a.

ciphertext B=0x7f7f5401726a\text{ciphertext B}=0x7f7f5401726a
Second ciphertextCiphertext is recomputed as plaintext XOR the reused toy keystream.Plaintext B48 bits / 6 bytes0x7061793d3930byte 0byte 1byte 2byte 301110000011000010111100100111101byte 4byte 50011100100110000byte-00x70byte-10x61byte-20x79byte-30x3dbyte-40x39byte-50x30Toy keystream48 bits / 6 bytes0x0f1e2d3c4b5abyte 0byte 1byte 2byte 300001111000111100010110100111100byte 4byte 50100101101011010byte-00x0fbyte-10x1ebyte-20x2dbyte-30x3cbyte-40x4bbyte-50x5aCiphertext B48 bits / 6 bytes0x7f7f5401726abyte 0byte 1byte 2byte 301111111011111110101010000000001byte 4byte 50111001001101010byte-00x7fbyte-10x7fbyte-20x54byte-30x01byte-40x72byte-50x6a

Only one plaintext byte changed

At the toy text level, plaintext B says pay equals 90.

pay B=90\text{pay B}=90
Second ciphertextCiphertext is recomputed as plaintext XOR the reused toy keystream.Plaintext B48 bits / 6 bytes0x7061793d3930byte 0byte 1byte 2byte 301110000011000010111100100111101byte 4byte 50011100100110000byte-00x70byte-10x61byte-20x79byte-30x3dbyte-40x39byte-50x30Toy keystream48 bits / 6 bytes0x0f1e2d3c4b5abyte 0byte 1byte 2byte 300001111000111100010110100111100byte 4byte 50100101101011010byte-00x0fbyte-10x1ebyte-20x2dbyte-30x3cbyte-40x4bbyte-50x5aCiphertext B48 bits / 6 bytes0x7f7f5401726abyte 0byte 1byte 2byte 301111111011111110101010000000001byte 4byte 50111001001101010byte-00x7fbyte-10x7fbyte-20x54byte-30x01byte-40x72byte-50x6a

Summary

Two different plaintexts have now been encrypted with the same toy keystream.

ciphertext B=0x7f7f5401726a\text{ciphertext B}=0x7f7f5401726a
Second ciphertextCiphertext is recomputed as plaintext XOR the reused toy keystream.Plaintext B48 bits / 6 bytes0x7061793d3930byte 0byte 1byte 2byte 301110000011000010111100100111101byte 4byte 50011100100110000byte-00x70byte-10x61byte-20x79byte-30x3dbyte-40x39byte-50x30Toy keystream48 bits / 6 bytes0x0f1e2d3c4b5abyte 0byte 1byte 2byte 300001111000111100010110100111100byte 4byte 50100101101011010byte-00x0fbyte-10x1ebyte-20x2dbyte-30x3cbyte-40x4bbyte-50x5aCiphertext B48 bits / 6 bytes0x7f7f5401726abyte 0byte 1byte 2byte 301111111011111110101010000000001byte 4byte 50111001001101010byte-00x7fbyte-10x7fbyte-20x54byte-30x01byte-40x72byte-50x6a