A container format for signed or enveloped cryptographic data, standardised as CMS in RFC 5652. In everyday PKI work it appears as .p7b/.p7c files that bundle one or more certificates — often a full chain — without any private key. SCEP also uses PKCS#7 envelopes to protect enrolment messages in transit.
PKCS#7
Public-Key Cryptography Standards #7 / Cryptographic Message Syntax