A method of electronically signing content, the method comprising: receiving, from a signing service, an electronic message comprising content to be signed (401, 503) and an identifier of at least one identity attribute (124, 403, 506); presenting at a signing device associated with a signer (i) the content to be signed (401, 503) and (ii) an attribute sharing item which, when accessed, causes the at least one identity attribute (124, 403, 506) to be provided, wherein the at least one identity attribute (124, 403, 506) is stored at an identity platform; detecting that the signer has accessed the attribute sharing item, and in response causing the identity platform to: determine if the signer is authorised to sign the content to be signed (401, 503); and if the signer is authorised, provide the at least one identity attribute (124, 403, 506) which uniquely identifies the signer to the signing device for presenting with the content to be signed (401, 503); detecting that the signer has initiated a signing action at the signing device; and transmitting the signing action with the at least one identity attribute (124, 403, 506) to the signing service which is configured to create an electronic signature including encrypting a hash of the content to be signed (401, 503) and the at least one identity attribute (124, 403, 506), wherein the attribute sharing item comprises a token containing attribute identifiers enabling the at least one identity attribute (124, 403, 506) to be accessed from the identity platform which holds a digital identity for the signer. receiving, from a signing service, an electronic message comprising content to be signed (401, 503) and an identifier of at least one identity attribute (124, 403, 506); presenting at a signing device associated with a signer (i) the content to be signed (401, 503) and (ii) an attribute sharing item which, when accessed, causes the at least one identity attribute (124, 403, 506) to be provided, wherein the at least one identity attribute (124, 403, 506) is stored at an identity platform; detecting that the signer has accessed the attribute sharing item, and in response causing the identity platform to: determine if the signer is authorised to sign the content to be signed (401, 503); and if the signer is authorised, provide the at least one identity attribute (124, 403, 506) which uniquely identifies the signer to the signing device for presenting with the content to be signed (401, 503); detecting that the signer has initiated a signing action at the signing device; and transmitting the signing action with the at least one identity attribute (124, 403, 506) to the signing service which is configured to create an electronic signature including encrypting a hash of the content to be signed (401, 503) and the at least one identity attribute (124, 403, 506), determine if the signer is authorised to sign the content to be signed (401, 503); and if the signer is authorised, provide the at least one identity attribute (124, 403, 506) which uniquely identifies the signer to the signing device for presenting with the content to be signed (401, 503); detecting that the signer has initiated a signing action at the signing device; and transmitting the signing action with the at least one identity attribute (124, 403, 506) to the signing service which is configured to create an electronic signature including encrypting a hash of the content to be signed (401, 503) and the at least one identity attribute (124, 403, 506), wherein the attribute sharing item comprises a token containing attribute identifiers enabling the at least one identity attribute (124, 403, 506) to be accessed from the identity platform which holds a digital identity for the signer.