A5/1 •A5/2 •ABA digital signature guidelines •ABC (stream cipher) •Abraham Sinkov •Acoustic cryptanalysis •Adaptive chosen-ciphertext attack •Adaptive chosen plaintext and chosen ciphertext attack •Advantage (cryptography) •ADFGVX cipher •Adi Shamir •Advanced Access Content System •Advanced Encryption Standard •Advanced Encryption Standard process •Adversary •AEAD block cipher modes of operation •Affine cipher •Agnes Meyer Driscoll •AKA (security) •Akelarre (cipher) •Alan Turing •Alastair Denniston •Al Bhed language •Alex Biryukov •Alfred Menezes •Algebraic Eraser • Algorithmically random sequence • Alice and Bob • All-or-nothing transform • Alphabetum Kaldeorum • Alternating step generator • American Cryptogram Association • AN/CYZ-10 • Anonymous publication • Anonymous remailer • Antoni Palluth • Anubis (cipher) • Argon2 • ARIA (cipher) • Arlington Hall • Arne Beurling • Arnold Cipher • Array controller based encryption • Arthur Scherbius • Arvid Gerhard Damm • Asiacrypt • Atbash • Attribute-based encryption • Attack model • Auguste Kerckhoffs • Authenticated encryption • Authentication • Authorization certificate • Autokey cipher • Avalanche effect
B-Dienst • Babington Plot • Baby-step giant-step • Bacon's cipher • Banburismus • Bart Preneel • BaseKing • BassOmatic • BATON • BB84 • Beale ciphers • BEAR and LION ciphers • Beaufort cipher • Beaumanor Hall • Bent function • Berlekamp–Massey algorithm • Bernstein v. United States • BestCrypt • Biclique attack • BID/60 • BID 770 • Bifid cipher • Bill Weisband • Binary Goppa code • Biometric word list • Birthday attack • Bit-flipping attack • BitTorrent protocol encryption • Biuro Szyfrów • Black Chamber • Blaise de Vigenère • Bletchley Park • Blind credential • Blinding (cryptography) • Blind signature • Block cipher • Block cipher mode of operation • Block size (cryptography) • Blowfish (cipher) • Blum Blum Shub • Blum–Goldwasser cryptosystem • Bomba (cryptography) • Bombe • Book cipher • Books on cryptography • Boomerang attack • Boris Hagelin • Bouncy Castle (cryptography) • Broadcast encryption • Bruce Schneier • Brute-force attack • Brute Force: Cracking the Data Encryption Standard • Burrows–Abadi–Needham logic • Burt Kaliski