What does ciphertext mean?
Ciphertext is the unreadable result of encrypting ordinary text, known as plaintext, using a cipher or cryptographic algorithm. Where plaintext is directly intelligible — a letter, a password, a web request — ciphertext appears as a seemingly random jumble of letters, numbers, or symbols that conveys nothing without the secret key needed to decrypt it. The term belongs chiefly to the vocabulary of cryptography and computer security: cryptographers analyze ciphertext to test a system's strength, attackers who intercept it hope to break it, and legitimate recipients reverse the process with the right key. Its everyday significance has grown enormously in the digital era, since virtually all secure online communication — banking, messaging, shopping — depends on converting sensitive data into ciphertext in transit. The word pairs naturally with verbs such as decrypt, break, intercept, and generate, and stands in direct contrast to plaintext.
nounEncrypted text: the scrambled, unreadable output produced when a cipher or encryption algorithm is applied to plaintext. Ciphertext can be converted back into readable form only with the correct key or method of decryption.
- The unintelligible output of an encryption algorithm, convertible back to plaintext only by decryption.
"Even if the attackers intercepted the message, all they saw was meaningless ciphertext."
"The intercepted transmission consisted entirely of ciphertext, useless without the decryption key."
"Modern TLS connections wrap every byte of a web request in ciphertext before it crosses the network."
The plural is uncommon but well-attested when referring to multiple distinct encrypted texts or samples under analysis.
"The researchers collected thousands of ciphertexts generated by the broken algorithm."
Every HTTPS page you load — including this one — arrives at your device as ciphertext that your browser silently decrypts billions of times a day.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of ciphertext
Ciphertext combines "cipher," meaning a code or system of secret writing, with "text." "Cipher" entered English in the late Middle Ages from Old French "cifre," ultimately tracing back through Medieval Latin "cifra" to Arabic "ṣifr," meaning "zero" or "empty" — the same root that gives us "zero" itself. As encryption became formalized as a science in the twentieth century, the compound "ciphertext" emerged as the natural counterpart to "plaintext," a pairing now standard across modern cryptographic literature.
How ciphertext is actually used
Ciphertext is technical vocabulary, standard in cryptography, computer security, and mathematics; it is rarely used in everyday conversation except metaphorically. It functions as both a count noun (a ciphertext, distinct ciphertexts) and an uncountable mass noun (the ciphertext was garbled).
Easily confused with ciphertext
Plaintext is readable, unencrypted text, while ciphertext is its scrambled encrypted counterpart.
A cryptogram is a puzzle meant to be solved for entertainment, whereas ciphertext is a serious product of encryption used to protect information.