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Key Pair Authentication

Last updated: 2022-03-30 16:22:18

    You can use secret_id and secret_key for authentication management of your APIs. As secret_id and secret_key appear in pairs, they are called secret_id/secret_key pair.
    You need to create a secret_id/secret_key pair before the authentication.

    Key Pair Authentication for API

    When creating an API, you can choose the authentication type as "key pair authentication". Then, after the API is released, only access requests to it initiated with the correct key pair can pass the authentication by API Gateway, while requests without the key or correct key pair cannot.
    After the API is created, you need to use the "usage plan" feature to bind the key pair to the API or the service where the API resides. For more information on the configuration, please see Usage Plan.

    Key Content

    Sample secret_id: AKIDCg*****j548pN. It is used to identify which key is used, participates in signature computation, and is reflected in the transfer process.
    Sample secret_key: ZxF2wh*****N2oPrC. It is used for signature computation, but is not reflected in the transfer process.

    Signature Computation

    Content to be delivered at last

    The HTTP request delivered at last contains at least two headers: Date/X-Date and Authorization. More headers such as source in a request are also workable.

    The value of Date header is the time constructed by HTTP request in GMT, for example: Fri, 09 Oct 2015 00:00:00 GMT.

    The value of X-Date header is the time constructed by HTTP request in GMT, for example: Mon, 19 Mar 2018 12:08:40 GMT. The value for timeout is 15 minutes.

    Source header represents the signature watermark value. You can enter any value for it or leave it empty.

    The Authorization header is in the format of Authorization: hmac id="secret_id", algorithm="hmac-sha1", headers="date source", signature="Base64(HMAC-SHA1(signing_str, secret_key))".

    The various parts of Authorization are explained as follows:
    hmac: a fixed part used to indicate the computation method.
    ID: the value of secret_id in the key.
    algorithm: the encryption algorithm. hmac-sha1 is supported now.
    headers: refer to headers that involve in signature computation, sorting by the order of actual computation.
    signature: the signature obtained after signature computation is completed, with signing_str as its content.

    Signature computation method

    A signature has 2 parts and is computed according to the specified encryption algorithm. Take hmac-sha1 algorithm as an example:

    Signature content

    First, generate the signature content, which consists of custom headers. It is recommended to include "date" at least in the header. But you can also include more headers.

    Headers are converted according to the following requirements and then sorted in sequence:

    1. The header name is converted to lowercase and followed by the ASCII character : and then an ASCII space character.
    2. Attach the value of the header.
    3. If it is not the last header that needs to construct a signature, attach ASCII new-line character \n.

    For example, if there are two headers involved in constructing the signature content (this example is for your reference only. Please fill in the fields as needed):

    Date:Fri, 09 Oct 2015 00:00:00 GMT
    Source:AndriodApp
    

    The generated signature content is as follows:

    date: Fri, 09 Oct 2015 00:00:00 GMT
    source: AndriodApp
    

    Computing a signature

    Base64(HMAC-SHA1(signing_str, secret_key)) algorithm is used to compute the signature content generated in the previous step to generate a signature, that is:

    • Using the signature content as input information, and secret_key content as the key, compute according to HMAC-SHA1 algorithm to get the encrypted signature content.
    • Convert the computed encrypted signature content to deliverable signature content using Base64.

    Using a signature

    As shown in Content to be delivered at last, at "signature" in the Authorization header, enter the signature computed in the last step.

    Notes

    header matching

    The headers in Authorization are the ones involved in signature computation. We recommend you convert them to lowercase and separate them by ASCII spaces. For example, if the headers involved in the computation are date and source, the format should be headers="date source"; if only the x-date header participates in the computation, the format should be headers="x-date".

    Signature content generation

    When arranging the content, please pay extra attention to the colon and space after the header name. If they are missing, the verification may fail. SecretId, SecretKey, URL, and Host should be replaced with your real information.

    Note:

    For signature demos for common programming languages, please see Developer Guide - Generating Signatures in Multiple Programming Languages.

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