3DS ReferenceProtocol & field guide

EMV 3-D Secure · Core specification 2.3.1.1

SDK Counter SDK to ACSsdkCounterStoA

SDK Counter SDK to ACS in Challenge Request (CReq).

Source edition: Core 2.3.1.1 · Type: String · Length: 3 characters · Minimum length: 3 · Maximum length: 3

Baseline in CReq Required

Varies by context. Requirement or applicability varies by channel or message category. Select a specific context to resolve it. Usage and conditions ↓

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Usage in CReq

Counter used as a security measure in the 3DS SDK to ACS secure channel. Note: The counter is the decimal value equivalent of the byte, encoded as a numeric string.

Format and scope

Type: String · Length: 3 characters · Minimum length: 3 · Maximum length: 3

Source components: 3DS SDK. Channels: 01-APP. Categories: 01-PA, 02-NPA.

EMV_3DS_CoreSpec_v2.3.1.1_20230530.pdf, Table A.1, PDF pages 280

Related FAQ notes

  • In cryptographic functions (Section 6.2), coded as 1 byte counting 0-255. In CReq/CRes messages, transmitted as decimal string padded to 3 digits. Example: byte 0x23 (35 decimal) → '035'. — FAQ 20 (EMVCo FAQ)

Transaction context

This reference covers the published source edition. Use the explorer to inspect this field and any applicable transaction conditions. Scheme programme requirements are not inferred from the protocol edition.

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Sources and related references

EMV_3DS_CoreSpec_v2.3.1.1_20230530.pdf, Table A.1, PDF pages 280

Source review status: carried-forward. Carried-forward material has not acquired a new verification claim.

Document fingerprint (SHA-256): 6fdf0aba3fc1a765f96b74dad4069d1e189969f38f0023647021687daf589d6b