Break it Down (Crypto)

Arch 6x64

Cyberchef magic + ROT13.

CDDC21{0h_mY_b4S3}

No Rotations

Monoalphabetic substitution.

CDDC21{sUbsTituTion_CiPhEring}

Nice Encryption

Cyberchef magic with known crib CDDC21.

(XOR each hexadecimal number with 0x71)

CDDC21{Wh0_wrot3_th!s_Thin6?}