Security Tools › PKI & Certificates › Signatures & CMS
Signatures and CMS
Open any CMS (PKCS#7) object, from signed data and certificate bundles to envelopes and timestamps; create a .p7s signature over text or a file, classical or post-quantum; and try hashing, HMAC, AES-GCM and ECDSA step by step.
- 3 free tools
- Nothing uploaded or stored
- CMS · PKCS#7 · RFC 5652
Signatures & CMS
Create and check digital signatures in the Cryptographic Message Syntax (PKCS#7) used by S/MIME, code signing, timestamps and SCEP.
CMS / PKCS#7 analyser .p7s · .p7m · .p7b · RFC 3161 New
Open any CMS (PKCS#7) object: signed data, certificate bundles, encrypted envelopes, timestamps and SCEP messages. See the signers, signed attributes and algorithms, and verify signatures — including ML-DSA (RFC 9882).
Detached signature? Add the original content
The file is read in your browser only.
Signer certificate not included? Add it here
OpenSSL equivalent: openssl cms -cmsout -print -inform DER -in file.p7s and openssl cms -verify -inform DER -in file.p7s -content file.txt -noverify
Sign with CMS / PKCS#7 digital signature creator New
Create a standard CMS signature (.p7s) over text or a file — classical or post-quantum. A one-time key pair and a self-signed signer certificate are made in your browser for each signature, so you can learn and test without exposing a real key.
Cryptography playground hash · HMAC · AES-GCM · ECDSA · random
See the building blocks of PKI work: hashing, message authentication, authenticated encryption and digital signatures. Change one character and watch the result change completely.
Hash
Hex
Base64
SHA-1 is shown for comparison only — it is broken for signatures.
HMAC
Tag
AES-256-GCM
Digital signature (ECDSA P-256)
Public key
Secure random
Hex
Base64
UUID v4