rnp-profile.json

{
  "symmetric": [
    "aes": {
      "key-length": [
        {
          /* anything less will score "unacceptable" */
          "predicate": "min",
          "levels": [
            {
              "level": 2,
              "value": 128
            },
            {
              "level": 3,
              "value": 192
            }
          ]
        }
      ]
    },

    /* disable SM4 */
    "sm4": 0
  ],

  "asymmetric": {
    "rsa": {
      /* different filtering parameters available to algorithms */
      "keysize": [
        {
          /* anything less will score "unacceptable" */
          "predicate": "min",
          "levels": [
            {
              "value": 1024,
              "level": 1
            },
            {
              "value": 2048,
              "level": 3
            }
          ]
        }
      ]
    }
  },

  "hash": {
    /* specifying a level as an attribute */
    "md5": {
      "level": 2,
    }

    /* specifying a default level */
    "ripemd-160": 3,

    "sha-1": {
      "valid": [
        {
        /* sha-1 is considered level 2 until 20220101 */
          "predicate": "until",
          "levels": [
            {
              "level": 2,
              "value": "20220101"
            }
          ]
        },
        /* sha-1 is considered level 1 (e.g. insecure) since 20220101 */
        {
          "predicate": "from",
          "levels": [
            {
              "level": 1,
              "value": "20220101"
            }
          ]
        }
      ]
    }
  }
}

I'm not sure i understand why the user is defining different levels?

The concept of "levels" allows the user application to define a mapping between conditions to some simple integer output. For instance, in one application 0 could mean "disabled", 1 could mean "accepted". In another application the scale could be 0 to 3, where 1 is "risky", 2 is "safe". It provides a flexible way for the application to determine the outcome based on the combination of algorithms.

If so, why not just specify a single policy on the rnp_ffi_t object, then if the user wants different levels, they can just instantiate multiple rnp_ffi_t objects, each with different policies.

This depends on what constitutes a "policy" or "profile". Or if one rnp_ffi_t can link multiple policies. The reason we went with a single policy with more complex provisions rather than multiple policies with simple provisions is that the mapping within a single policy is more likely to be consistent. On the other hand, a set of simple policies linked into one "complex policy" also works.

In any case, the construct of a profile/policy goes:

• filter => level
• a filter can specify acceptance or rejection
• the level is application-specific and has no inherent meaning in RNP

the sop draft specifies that it's looking at signature dates, not the current time

Good point, there is a distinction between filtering on signature date and current time. We need to make that distinction.

does it mean "stop making signatures with this hash at this date?

So far we have only specified filtering criteria for content validation (received content), instead of content generation. Would you find it useful to specify behavior such as "stop making signatures with this hash at this date"?

The following shows usage for both production and consumption of algorithms, with examples of how a client can interpret the values.

{
  "production": {
    "symmetric": {
      "aes": {
        "key-length": [
          {
            /* client can interpret as: We show a green tick if user chooses "AES 192", yellow question mark if "AES 128", red cross otherwise */
            /* anything less will score "unacceptable" */
            "predicate": "min",
            "levels": [
              {
                "level": 2,
                "value": 128
              },
              {
                "level": 3,
                "value": 192
              }
            ]
          }
        ]
      },

      /* client can interpret as: We don't generate anything with SM4 */
      "sm4": 0
    },

    "asymmetric": {
      "rsa": {
        /* different filtering parameters available to algorithms */
        "keysize": [
          {
            /* client can interpret as: We don't provide options to generate RSA keys with < 1024 bits, and we show a green tick if >= 2048 bits */
            "predicate": "min",
            "levels": [
              {
                "value": 1024,
                "level": 1
              },
              {
                "value": 2048,
                "level": 3
              }
            ]
          }
        ]
      }
    },

    "hash": {
      /* specifying a level as an attribute */
      /* client can interpret as: Anything with md5 is a yellow question mark */
      "md5": {
        "level": 2,
      }

      /* client can interpret as: Anything with ripemd-160 is a green tick */
      "ripemd-160": 3,

      "sha-1": {
        "valid": [
          {
          /* sha-1 is considered level 2 until 20220101 */
          /* TODO: expand on the date time value --- take into account timezones? local time? */
            "predicate": "until",
            "levels": [
              {
                "level": 2,
                "value": "20220101"
              }
            ]
          },
          /* sha-1 is considered level 1 (e.g. insecure) since 20220101 */
          {
            "predicate": "from",
            "levels": [
              {
                "level": 1,
                "value": "20220101"
              }
            ]
          }
        ]
      }
    }
  },
  "consumption": {
    "symmetric": {
      "aes": {
        "key-length": [
          {
            /* anything less will score "unacceptable" */
            "predicate": "min",
            "levels": [
              {
                "level": 2,
                "value": 128
              },
              {
                "level": 3,
                "value": 192
              }
            ]
          }
        ]
      },

      "sm4": 0
    },

    "asymmetric": {
      "rsa": {
        "keysize": [
          {
            "predicate": "min",
            "levels": [
              {
                "value": 1024,
                "level": 1
              },
              {
                "value": 2048,
                "level": 3
              }
            ]
          }
        ]
      }
    },

    "hash": {
      "md5": {
        "level": 2,
      }

      "ripemd-160": 3,

      "sha-1": {
        "valid": [
          {
          /* client can interpret as: The signature, if made with sha-1 on or before (or just before? TODO) 20220101, is considered level 2 */
            "predicate": "until",
            "levels": [
              {
                "level": 2,
                "value": "20220101"
              }
            ]
          },
          /* client can interpret as: The signature, if made with sha-1 on or after (or just after? TODO) 20220101, is considered level 1, or "insecure", or "red cross", etc. */
          {
            "predicate": "from",
            "levels": [
              {
                "level": 1,
                "value": "20220101"
              }
            ]
          }
        ]
      }
    }
  }
}